Review: Deeper Pro+ Fish Finder

I received a demo model Deeper Pro Plus sonar fish finder to test and I thoroughly enjoyed using it. Saddened me to give it back, in fact.Here’s my review…
The Deeper Pro and Deeper Pro Plus are available through Mantality. Both of these are superior to the 3.0, with a reception of up to 100 metres—double the range of the 3.0—and the ability to create bathymetric maps.

 the new and improved Deeper Chirp is now available.


  • Deeper Pro – R4,899
  • Deeper Pro Plus – R5,299
  • Deeper Chirp – R5,499


Buy Deeper Pro


The Deeper is a great product. (I’m peeved that the demo model Mantality sent me had to go back.)

It has it’s drawbacks, but for a tool this size to give the type of functionality it offers, and do it so well, is remarkable.

I tested the Deeper in a number of fishing spots. I cast it into lagoons, a river, into surf and from the rocks. It didn’t do too well from the rocks or in the surf, but the swell was on the large side (two to four feet).

In lagoons, a river and from the bridge it performed admirably and surprised me with how little I knew about my favourite fishing spots.

What stands out most about the Deeper Pro Plus is the bathymetric mapping function. This allows you to create an underwater topographical map of a fishing spot, which becomes invaluable for future fishing outings. I took this function for a spin a few times, and despite it being off by a few metres (in South Africa; not sure what it’s like elsewhere), it does a fine job of delivering a useful map.

I think, however, that creating a bathymetric map with the Deeper should prove much easier on the water than from land. If you have a boat or kayak, mount the Deeper Pro (you don’t need the Pro Plus for on-water bathymetric map creation) onto your craft with the Deeper flexible arm (sold separately) and map out a fishing spot. The maps are kept in your Deeper app’s history and freely available for future use.

The Deeper app’s notes function, which allows you to add a note, to which it adds a date, time and location automatically, and to which you can add pictures and comments, is also useful. This is a great way to create a fishing diary.

Why use a fish finder?

Although I set out to use the Deeper as a fish finder, I ended up using it more for profiling the waters we frequent. It’s fascinating to see your favourite fishing spot from a whole different angle.

Why is profiling important?

Because we fish artificial lures (I make lead-free bucktail jig heads), we target predatory fish exclusively. These include garrick, kob and shad.

We know that predatory fish utilise structure to conceal themselves from their prey. Profiling the bottom of a fishing spot reveals where these predators might be lying in wait for an unsuspecting victim. Drop-offs, holes and other structures offer the perfect hideout for the fish you’re hoping to catch. These structures are impossible to see from water’s edge.

You could troll the region with a lure, but this leaves you blind and guessing, unlike a good fish finder (such as the Deeper). You also lose lures this way.

Another important factor is the depth you find fish at on any given day. This is impossible to determine quickly and effectively, unless you use a fish finder.

However, even if your Deeper doesn’t produce a single fish image while in use, the data it collects is invaluable.

Therefore, a tool such as the Deeper portable fish finder becomes a vital link in the chain of fishing success.

The Deeper changed the way I approach a fishing spot. It makes it easy to see where the hot spots might be and at which level the fish can be found. Turns guessing into knowing.

Important note: Make sure you use a good rod and reel for casting the Deeper fish finder. This is crucial. Get a reel that doesn’t require you to keep an eye on it while you’re trying to read the Deeper. I didn’t have a good reel at my disposal for this purpose. Using the Deeper turned into a two-man operation.

Deeper highlights

The Deeper Pro Plus stands out for a number of reasons:

  • Create bathymetric maps of your favourite spots. This is worth GOLD.
  • It’s portable.
  • It’s easy to use.
  • It does a great job of showing you where the fish are.
  • Create notes in the app, which adds date, time and position automatically and allows you to add photos and information. This is great for keeping a fishing diary.
  • Long battery life.


There were a few minor irritations. If I opened the Deeper app while the Deeper device was charging, my phone connected to the Deeper automatically. The problem was, once the Deeper’s Wi-Fi was active, my home Wi-Fi didn’t stand a chance. No matter what I tried, the phone kept connecting to the Deeper.

The other issue was that the Deeper app switched on Bluetooth automatically when I entered the app. Since it uses a Wi-Fi signal, I couldn’t understand why it would need Bluetooth too.

I couldn’t work out how to check the weather for a specified location.

The standard map seems utterly useless. It’s void of any information.

These are negligible issues though. This is a fish finder, after all. Besides, features and fixes are an app upgrade away.

Warranty info

This from Clinton at Mantality, which is a response he received directly from Deeper:

We offer standard 1-year warranty. It would be great if you could track the serial numbers (products you receive from us). As sometimes happen that people bring products purchased from other countries and ask for warranty. We can also track it from our side.

It would be great that people could contact someone from your company or our customer service in case they have problem, usually it’s not about the product. It is about how to use. If we can’t help online then they should bring it to you or the retailer where the product was bought.

The box when it arrived

The demo model Mantality sent me was brand new, therefore the contents were in perfect order. True to Mantality’s standards, the packaging didn’t show a hint of damage.

Inside the box

This is what comes with your purchase of a Deeper Pro Plus:

  • One Deeper smart sonar device.
  • One micro USB charging cable.
  • Two attachment bolts (for attaching line to, in order to cast the Deeper sonar).
  • One neoprene pouch.
  • Three booklets.
    • Two quick guides, in different languages, showing you how to set up the Deeper.
    • A safe usage and regulations guide, which Deeper claims is important reading.
    • The guides are available in digital format inside the app.

Deeper sonar models

Deeper currently makes three models, one of which, the Deeper 3.0, is not available in South Africa (not through Mantality, in any case), due to it not being approved by ICASA (it uses Bluetooth).

The Deeper Pro and Deeper Pro Plus are superior to the 3.0 though, since the 3.0, using Bluetooth only, gives you half the range of the Pro and Pro Plus. The 3.0 can’t create bathymetric maps either.

Differences between the Deeper Pro and Deeper Pro Plus

Deeper Pro Deeper Pro Plus
Price R4,899 R5,299
Mapping options Boat mode bathymetric mapping function only Onshore bathymetric mapping option too

The only difference between the Deeper Pro and Pro Plus (besides the price) is the mapping function. The Pro Plus boasts an internal GPS receiver which allows you to create bathymetric contour maps, even if you’re using it from land.

The Deeper Pro allows you to create bathymetric maps too, but only when you’re on a boat, since it uses your smart phone or tablet’s GPS.

If you create a bathymetric map with the Deeper (Pro or Pro Plus), it’s stored for later access.

It’s up to you to decide whether it’s important to have the ability to map your fishing spot from the shore. I think it’s one of those functions that, once used, you wouldn’t want to go without it. It’s a powerful tool.

Deeper Pro Plus specs

Saltwater friendly? Yes
Reception range 100m
Reception type Wi-Fi
Depth range 80m
Minimum usage depth 1m
Diameter (smallest) 64mm
Diameter (largest) 67mm
Weight (without attachment bolt) 98g
Weight (with attachment bolt) 101g
Sonar type Dual beam
Sonar beam angles 15 degrees and 55 degrees
Ping rate 15/s
Operating temperatures -20 degrees Celsius to 40 degrees Celsius
Battery 3.7V rechargeable lithium polymer
Battery charge time (claimed) Two hours
Battery life (Without GPS, frequency 290kHz) Six hours
Battery life (without GPS, frequency 90kHz) Five hours thirty minutes
Battery life (with GPS, frequency 290kHz) Five hours thirty minutes
Battery life (with GPS, frequency 90kHz) Four hours thirty minutes
Operating system compatibility Android phone and tablet – from Android 4
iPhone and iPad – from iOS 8
Body material ABS

Before using the Deeper

A few things to note before you set out to catch the big one with the help of the Deeper.

Charge your Deeper

Before taking to your favourite fishing spot, put the Deeper on charge. Don’t wait until just before you head out. The Deeper takes a while to charge.

Deeper’s documentation states that expected charging time is two hours. This was not the case for me. I plugged it in and checked on it every few hours. Eventually I went to bed and left it to charge overnight. The LED was green the next morning, indicating full charge.

How to check battery level

You can view the Deeper sonar’s battery level inside the app (shows only when the sonar device is in the water or plugged in for a charge and connected to the app). Alternatively, you can unscrew the Deeper sonar’s cap, wet your finger and touch both the metal pins at the bottom of the device simultaneously. Check the LED light’s response as an indication of battery charge level.

The Deeper app shows the Deeper sonar's charge level when the sonar is plugged in to charge

The Deeper app shows the Deeper sonar’s charge level when the sonar is plugged in to charge.

Charging tips

  • Don’t leave the Deeper plugged in for too long once it’s charged. They claim that this could reduce battery life.
  • Don’t cover the device (or the charger) while it’s charging. This could lead to overheating.
  • Check to see that the Deeper’s charging port is dry before you charge it.

How to charge the Deeper

Here’s how to charge your Deeper fish finder:

  1. Unscrew the cap from the body.
    • You’ll notice a sticker covering the charging port telling you that the Deeper needs to be charged every six months. (You can discard of the sticker.)
  2. Lift the charging port rubber cap.
  3. Insert the micro USB (which obviously needs to be plugged in).
  4. An LED indicator glows green if the Deeper is fully charged; flashes orange while it’s charging.
LED colour meanings

When you first charge the Deeper, the LED light might flash red and all sorts of other colours. According to Deeper documentation, a red light indicates that the device needs a service. The demo model’s LED flashed red for a while (and blue, and orange) when I first plugged it in, but it certainly didn’t need a service. Not sure what that was about.

Orange blinking light
Indicates charging level. Higher frequency blinking indicates that the Deeper is nearing full charge.
Green light
The Deeper fish finder is fully charged and ready for use.
Blue light
It’s too cold for the Deeper sonar to charge. The Deeper can’t be charged at minus three degrees Celsius or lower. That shouldn’t be a problem for people living in South Africa.
Your Deeper fish finder needs a service.

Safe usage and regulations

A few guidelines to help you keep your Deeper in good condition:

  • Use a solid rod, a good reel and strong line for casting the Deeper. You don’t want it snapping off. I snapped it off twice. Never in my life have I prayed so hard to find a missing item.
  • Periodically check that the main seal is in good condition. If the seal is broken, the Deeper is not waterproof.
  • Don’t disassemble the Deeper yourself. If you pick up trouble with the device, send it back to the supplier.
  • Don’t attempt to remove the Deeper’s battery.
  • Don’t kick the device, step on it, drop it or puncture it.
  • If the device shows significant damage, don’t use it.
  • If the device emits rattling or flowing sounds when shook, don’t use it.
  • Don’t cast the Deeper into other fishermen, or across their lines. It’s bad for your teeth.
  • Don’t submerge the Deeper.
  • Don’t use the Deeper’s depth reading or built-in map feature to navigate your boat.
  • Don’t use the Deeper outside of the temperature range of -20 degrees Celsius to 40 degrees Celsius.
  • Don’t leave the Deeper inside a car on a hot day.
  • Don’t leave the Deeper out in the sun for prolonged periods of time.

Please read the Safe Usage and Regulations booklet that comes with the Deeper fish finder (or read the electronic versions inside the app).

How to access the user guide on the Deeper app:

  1. Tap on Settings.
  2. Tap on Read manual.
  3. Choose your language.
  4. Read the guide for some valuable insights.

Things to know about using the Deeper Pro Plus

Keep a few things in mind when you use the Deeper fish finder:

  • There’s no on or off button on the Deeper sonar device. It connects to the Deeper app automatically once it hits the water or while it’s charging (and the app is open).
  • It needs a Wi-Fi signal to connect to your phone.
    • Does not require data to be used as a sonar.
  • It can be used with Android or Apple.
    • iOS 8 or later.
    • Android 4 or later.
  • Official documentation claims that the Deeper cannot be used in small areas such as in buckets, aquariums or water tanks. Why anybody would want to use it in that way…
  • You need to download the Deeper app and create an account before you’re able to use the Deeper fish finder.
  • Water blocks the Wi-Fi signal, so the Deeper won’t work too well in stormy weather or for surf fishing (if the waves are big). Won’t work if you dunk it underwater.
  • Steel, reinforced concrete and other heavy materials block Wi-Fi signal.
  • Your phone’s Wi-Fi beam direction is important. If you experience reception problems, experiment with the way you hold your phone.

Using the Deeper

The Deeper is super simple to use. It’s mostly plug and play. You cast, connect and start collecting data.

How to read the Deeper

When using a fish finder, you need to adapt your thinking a little bit.

Your screen shows a 2D display, but remember that the Deeper records at 15 degrees (290kHz) or 55 degrees (90kHz) (depending on your settings) in all directions.

A fish finder works by echoing sound off of the bottom of wherever it’s used. In the case of the Deeper, the signal is interpreted by the sonar device and sent back to the mobile app. Data enters the Deeper app’s screen from the right hand side and exits on the left.

Here’s the thing though: it’s not a liquid signal (for lack of a better explanation). The signal, even though it’s sent out at a 15 or 55 degree circular arc, returns the moment it encounters its first obstacle.

Data enters the right side of the screen and exits on the left

Data enters the right side of the screen and exits on the left.

The dead zone, or, The Case Of the Invisible Fish

When a sonar device sends out a beam to the bottom, that beam hits the first thing it finds and returns to the sonar. This means that, if you make use of the Deeper’s 55 degree angle (90kHz) setting, you could miss potential holes, ridges or even fish.

So be careful of trying to cover too much ground with the 55 degree setting. I’d suggest using the 15 degree setting, even though it might take a little longer to scan an area.

These issues are not restricted to the Deeper only. It’s common problems with standard sonar systems. You simply have to learn how to read a fish finder properly to make up for the tool’s shortcomings.

Soft bottom, hard bottom

The Deeper is able to return bottom density data. The harder the bottom, the stronger the signal.

On the Deeper’s screen…

  • Orange shows the hardest type of bed.
  • Brown shows a medium hard bed.
  • Black shows a smooth bed.
  • Green shows weed beds or vegetation.

This is an important function. Some species of fish have a preference for hard beds; others prefer softer beds.

So while you’re scanning a region you may think shows potential, even if no fish show up on your sonar, profile the spot for future targeting.

A hard bottom shows up as orange on the Deeper, while a soft bottom shows up brown, a smooth bottom as black and vegetation and weed beds as green

A hard bottom shows up as orange on the Deeper, while a soft bottom shows up brown, a smooth bottom as black and vegetation and weed beds as green.

Getting the most accurate interpretation of a fish

For obvious reasons, the Deeper’s representation of a fish shouldn’t be seen as an exact science. It’s only a representation. In fact, what a fish finder “sees” is the fish’s swim bladder. So take what you see on the screen with a grain of salt.

The Deeper app gives you the option of adding a fish icon whenever it “sees” a fish. However, this, apparently, is not the most accurate representation of a fish.

To get the most accurate representation of a fish, do the following inside the Deeper app:

  1. Click on the quick settings button on the left of the screen.
  2. Choose Detailed Smart Imaging.
  3. Untick the Fish Icons option.

Some thoughts about this setting.

If you turn off fish icons, you’ll have to look for arcs. Here’s the thing though: if you’d like to see even small arcs, you’ll need to increase the app’s sensitivity setting to as high as the spot you’re fishing allows.

Now, you might be tempted to think that the longer an arc, the bigger the fish. This is not the case. The THICKER an arc is, the bigger the fish.

The Deeper allows you to set a fish icon, as can be seen in this screenprint

The Deeper allows you to set a fish icon, as can be seen in this screenprint.

Open the quick setting menu on the left of the Deeper's screen, choose Detailed Smrt Imaging and untick the Fish Icons option

To get the most accurate reading for a fish, open the quick setting menu on the left of the Deeper’s screen, choose Detailed Smart Imaging and untick the Fish Icons option.

If you turn off fish icons, look for arches that represent fish

If you turn off fish icons, look for arches that represent fish.

Difference between low frequency and high frequency

The Deeper gives you two frequency options: 90kHz and 290kHz.

A fish finder’s signal resembles the shape of a cone. The deeper the signal goes, the wider it arcs.

The 90kHz frequency has a 55 degree arc. It picks up a wider area, but it’s not as accurate. Remember, the signal returns the moment it hits something. It’s not a liquid signal part of which continues on to the bottom.

The 55 degree setting is great for getting a quick general overview of an area, but for more accurate fish finding or bottom profiling I’d suggest using the 290kHz setting.

The 290kHz frequency has a 15 degree arc. The beam being sent out doesn’t go out at such a great angle. It’s a more concentrated setting. It allows you to see more detail than with the 90kHz setting.

I used the 90kHz setting in the Kromme river, and then switched to 290kHz. The water was around 1.5m deep. I much preferred the 290kHz setting, since the 90kHz setting didn’t display comfortably. Setting the device to 290kHz normalised the display.

Watch the below video for some top-notch information about how the Deeper works.

Choose between 90kHz and 290kHz in the menu on the left hand side inside the Deeper's app

Choose between 90kHz and 290kHz in the menu on the left hand side inside the Deeper’s app.

Deeper sonar sensitivity setting

To the left of the Deeper app’s screen, when you click on the quick settings button, you’ll notice a sensitivity slider at the bottom.

This is set to a default of 75 per cent when you download the app.

The higher the sensitivity, the more detail is shown.

You’ll have to choose a setting that’s comfortable in your situation. Keep in mind that, if you switch off fish icons, you need to allow for as much detail as possible, in order to pick up fish arcs. This means that a setting of 75 per cent might not be sufficient.

Set the Deeper's sensitivity in the menu on the left hand side inside the Deeper's app. The default setting is 75%, which should be fine for most situations

Set the Deeper’s sensitivity in the menu on the left hand side inside the Deeper’s app. The default setting is 75%, which should be fine for most situations.

Make sure the Deeper is waterproof before you use it

The makers of the Deeper made it easy for you to ensure that your Deeper is watertight before you use it.

Just line up the text on the side of the Deeper’s cap with the text on the side of the Deeper sonar and your device is good to go.

Line up the text on the Deeper device's cover with the text on the Deeper device itself and your device is watertight

Line up the text on the Deeper device’s cover with the text on the Deeper device itself and your device is watertight.

What to cast the Deeper with

You could use a rope to sling the Deeper into the water, but a fishing rod gives you much greater distance. Use a thick fishing line to ensure that the Deeper doesn’t snap off when you cast.

My Deeper casting setup

My wife and I love to fish. However, we confine ourselves to light tackle lure fishing for a number of reasons.

The problem is, a light tackle rod won’t handle the Deeper sonar well, since it weighs in at a 100 grams. My seven foot rod casts only up to 28 grams comfortably. Anything above that does not cast well. You need a stiff, strong rod to handle this sonar.

Fortunately, I found an old Kingfisher Strikeforce boat rod in the garage, as well as a Penn 155 conventional reel. This setup handles the Deeper sonar with ease. It wasn’t easy to cast with the Penn, nor was it easy to reel in and keep an eye on the Deeper app. But I used what I had to do what needed to be done.

For the purpose of casting the Deeper device I’d recommend you get yourself a spinning reel (5000 series or larger) or a baitcaster loaded with overly thick fishing line.

Be warned, using a good casting setup for the Deeper is imperative. I sent the Deeper flying, twice. The line got jammed on my reel, a snap echoed in my ears and the next moment a Deeper disappeared into the distance. The first time it happened it took me a healthy walk and much prayer to get it back. Fortunately it landed in water both times.

I used a short stiff boat rod along with a Penn 155 reel to cast the Deeper with

I used a short stiff boat rod along with a Penn 155 reel to cast the Deeper with.

Which type of knot to use to tie your line to the Deeper

I used the Palomar knot to connect my mono-filament fishing line to the Deeper. Worked perfectly fine. Even when I snapped the Deeper off, it wasn’t the knot that broke. The line snapped.

You could attach a quick-release snap swivel to the end of your line and clip the Deeper onto your line if you wish. I didn’t see the need though.

A standard palomar knot works fine with the Deeper fish finder

A standard palomar knot works fine with the Deeper fish finder.

Learn how to tie a Palomar…

How to cast the Deeper

Casting the Deeper sonar isn’t different from casting a heavy lure or bait. However, I’d suggest taking a side casting approach to casting the device, if you don’t do so already.

Sometimes, when you cast, the line gets stuck somewhere between your fingers, the reel and the fishing rod’s eyes.

If you cast from the side, rather than over your shoulder, you don’t run the risk of slamming the Deeper into the ground, which is a mishap even seasoned fishermen can’t always avoid.

Attachment bolt position

The Deeper sonar has three threaded holes into which you can screw an attachment bolt, one dead centre at the top of the device, another a few degrees down on the side of the device and one near the bottom of the device.

You attach your fishing line to the attachment bolt. Each hole represents a different fishing position:

  • The top-most hole is used for attaching the bolt if you’re fishing from a bridge.
  • The middle hole is used for attaching the bolt if you’re fishing from a boat.
  • The bottom hole is used for attaching the bolt if you’re fishing from the shore.

The Deeper’s position in the water plays an important role in how well it sends a signal to your phone. Use the correct hole for each situation.

Deeper operating modes

The Deeper fish finder has four modes:

Inactive mode
Default mode. In this mode the Deeper is not discoverable on Wi-Fi.
Stand-by mode
Your Deeper is in the water, but not connected to your smartphone or tablet. It can be discovered and connected to via Wi-Fi.
Operating mode
Your smartphone or tablet is connected to the Deeper. The device is in water and scanning.
Charging mode
Your Deeper is plugged in and charging.

The Deeper sonar device does not have an indicator to show which mode it’s in. You’ll see this info inside the app.

How to connect the Deeper sonar to the Deeper app

The Deeper sonar needs to be in water of at least one metre deep in order for the app to start working as a fish finder.

Follow these steps to start using the Deeper as a fish finder:

  • Open the Deeper app on your phone.
  • Cast the Deeper into your water of choice (minimum depth of one metre).
  • The app should connect automatically with the Deeper sonar and start showing feedback.

According to Deeper’s documentation, some devices require a Wi-Fi password to connect. If this is the case for you, navigate to your Wi-Fi settings and type in the following password: 12345678.

That should connect the app to the device.

The app doesn’t need to be connected to the sonar to offer you other functionality, such as taking photos or checking your scan history.

Fishing with the Deeper fish finder

Up until here it’s all been theory. What does the Deeper do in real-world scenarios?

I took the Deeper on a few fishing excursions. Here’s the feedback…

Using the Deeper in a lagoon

Note: If you’re fishing from the shore, make sure the attachment bolt is screwed into the bottom hole.

We fish mostly estuaries and lagoons. The Deeper is perfect for this type of scenario.

I used the Deeper at two lagoons, the Kabeljouws lagoon and the Aston Bay lagoon. It was a horribly windy day; not exactly the type of weather suited to using a fish finder. Nevertheless, I cast the Deeper to see if it would work.

Despite choppy conditions, the Deeper returned accurate data. It gave depth readings and even showed some fish.

Does the Deeper work in a tidal river?

Yes and no.

I took the Deeper to the mouth of the Kromme river in St Francis Bay, two hours before low tide. I cast it out and tried to connect. It didn’t work as well as I’d hoped.

The Deeper was swept seawards by the tide, which, by the time I had arrived, was already calming. The problem is, when your line tightens as the Deeper drifts away from you, the outgoing water forces the Deeper under and it loses signal.

For reasons unknown the app took long to connect to the device. By the time it did connect, my fishing line was taut and the Deeper device being forced underwater.

I ended up profiling the mouth of the St Francis canal, which exits into the Kromme river. The water here was calmer and the Deeper worked well.

If you want to use the Deeper in a tidal river, it’s best to use it once the tide has settled. Alternatively, cast out the Deeper device and walk along the bank while it’s being moved by the tide.

Even better, use it from a boat; should work fantastic.

Using the Deeper from a bridge

Note: before you cast the Deeper from a bridge, make sure that the attachment bolt is attached to the top-most attachment hole on the device.

This exercise turned out to be quite successful. I cast the Deeper from the Kromme river bridge. It gave a great reading and even picked up a few fish. I walked along the bridge and managed to profile a region underneath the bridge we often fish.

Can the Deeper be used in the sea?

Yes and no.

I took the Deeper to Kabeljouws beach, walked out onto a reef adjacent to the beach and cast it out. This gave mixed results at best.

I then took the Deeper onto the surf, where I cast it into a promising hole. This didn’t work at all.

We drove out to Cape St Francis and parked at the lighthouse. I walked onto the rocks in front of the lighthouse and cast the Deeper out. I did this twice. The first time the app connected to the device and sent back a signal, but the second time the Deeper didn’t connect at all.

It was clear from this exercise that using the Deeper from the surf or from a reef is not a good idea if the surf is sizable.

What was the surf size when I used the Deeper? According to Magic Seaweed, the surf at the time of testing was in the two to four foot region.

If you plan on using the Deeper from the surf or from rocks, don’t do it if the surf is too big. The Deeper keeps getting dunked under water and won’t connect successfully.

Using the Deeper from a boat

Unfortunately I don’t own a boat, therefore testing it from one wasn’t possible. If you do use it from a boat, make sure the app’s settings are correct. Here’s what you should do:

  1. Tap on Settings.
  2. Tap on Sonar mode, beneath the SONAR heading.
  3. Choose Boat mode.
  4. Attach the bolt to the middle hole on the Deeper.

Deeper manufactures a flexible arm that you can attach to your boat or kayak. This arm allows the Deeper device to bob along on the side of your craft, and stops it from being submerged.

Deeper sonar maintenance

It’s simple to keep the Deeper sonar ship shape. If you use it in saltwater, simply rinse it under running freshwater when you get home. That’s about it.

To be honest, I’m too lazy to do even that. But this little fish finder is tough; should last for many years.

If your Deeper starts giving trouble, send it in for a service or repairs. Don’t attempt to fix it yourself.

The Deeper app up close

The Deeper sonar is useless without the app. To use the sonar you need a smartphone capable of using the app (iPhone or iPad with iOS8 or later; Android phone or tablet with Android OS 4 or later). In order to use the app’s additional functions (not just the sonar), you need data.

You also need to sign up for an account with Deeper before you can use the app. Take these steps:

You’ll receive an email from Deeper with a confirmation link which you need to respond to.

Information sent to the Deeper app

Some information is only present on the Deeper app’s screen if the Deeper device is in the water and connected.

For instance, water temperature and the Deeper device’s battery level only show when the Deeper device is in water.

If you’ve set the app to show fish icons, you’ll notice a number above the fish icon. This shows the depth of the fish.

The app’s depth scale adjusts automatically. If there’s a sudden drop-off, the app’s scale will update to reflect the change in depth.

App icon functions

At the bottom left of the app you’ll notice three icons (see the picture below).

Here’s what those buttons do:

  • The sound button mutes / un-mutes the device’s sound.
  • The Zzz icon puts the Deeper device into low power consumption sleep mode or wakes it from this mode.
  • The circle with three signal beams allows you to search for the device and connect to it (which it usually does automatically), if it’s in water or plugged in and charging.

The sound button, the low consumption button and the search and connect button on the Deeper fish finder

The sound button, the low consumption button and the search and connect button on the Deeper fish finder.

Deeper app functions

The Deeper offers you more than a fish finder. There’s a map function, calendar, camera, weather, note taking functionality and scan history.

Using some of these functions requires you to have internet access.

We’ll start with the Deeper’s ability to map. This is by far the most important function of the Deeper, in my opinion.

Deeper maps

There are two sides to the Deeper’s mapping function. One, in my opinion, is useless, the other invaluable.

Let’s start with the hopeless map function first, and then get to the good stuff.

The Deeper’s Map option in the top menu is utterly useless. When you tap on Maps, you’re presented with a screen showing a cross on what looks like a typical Google map. (They use Nutiteq as their map provider, not Google, by the way.)

To the right of the screen is a selection field where you can choose what you’d like to see on the map. This includes shops, fishing places, wharves, parking spots, picnic spots, rent (???), weather and info spots.

I was expecting all sorts of icons to pop up. None did.

OK, so maybe it’s because I find myself in an insignificant location. Let’s zoom out and head over to New York. They have a slightly larger population than Jeffreys Bay.

Still nothing.

OK, let’s place the Deeper sonar on charge and connect to it with the app. Perhaps that’ll produce something.


I have no idea what the Deeper’s Map function is useful for. It doesn’t seem to work at all.

I’d love to know whether users in other countries experience the same non-functionality from Deeper’s map.

You can download maps for offline use, but if it doesn’t show anything, what’s the point? Here’s how to do it, in any case, if you have time and bandwidth to waste.

How to download maps for offline use

To download a map for offline use, do the following:

  1. Tap on settings.
  2. Tap on Offline Maps.
  3. Tap on a region.
  4. Tap on a sub-region.
  5. Tap on the Download button for the region you require.
    • You can delete a map if you so wish.
How to access an offline map

There’s no special access point for downloaded maps. You simply select the Maps option in the top menu and use as if you were online.

How to create a bathymetric map

This is the good stuff.

The Deeper Pro Plus allows you to create bathymetric maps of your favourite fishing spots. In my opinion, this is the Deeper’s best function.

You can do this with the Pro and Pro Plus, but the Pro Plus allows you to do it from shore. No need for a boat.

Note: The Deeper Pro Plus’ bathymetric scan is still in beta mode. However, you won’t have to buy a new Deeper device once this functionality has matured. Just wait for a software update for the app.

What is a bathymetric map?

A bathymetric map is an underwater topography map.

Serious anglers know that they should pay special attention to the underwater topography of a fishing spot. As mentioned elsewhere in this article, gathering (and storing) information of your favourite spot’s bottom is near impossible without a sonar device, and yet, crucial.

To create a bathymetric map with your Deeper Pro Plus, follow these steps:

  1. Open your Deeper app.
  2. Cast your Deeper into the water.
  3. Tap on Settings in the top menu.
  4. Tap on Sonar mode.
  5. Choose Onshore GPS mode.
    • As of writing this article, this function is still in beta. Works though.
  6. Go back to the main screen.
    • The screen is now split, with the sonar image taking up the right half and a normal map taking up the left half.
    • A little icon in the shape of a man shows where you’re standing (this is your mobile device’s internal GPS doing its thing).
    • Another icon shows your Deeper device.
  7. Wait for the GPS to connect. The small orange button at the top right hand corner of the map indicates that it’s not connected. Once it’s connected the button turns green.
  8. Start to slowly retrieve the Deeper device.
    • You’ll notice that the icon representing your Deeper device moves towards the icon representing you.
    • While this is happening, the Deeper is collecting data and creating a bathymetric map which you can access at any time.

This, in my opinion, is what REALLY makes the Deeper fish finder diamond crusted gold. Forget spotting fish. This contraption, smaller than a tennis ball, allows the Average Joe to walk to his favourite fishing spot and, with the tap of a few buttons, create a decent bathymetric map which he can access at any time from a device that fits into his top pocket.

I managed to create a bathymetric map of the exit of the Cape St Francis canal. Notice that it's off by a few metres. I was standing on the sandbank when I created this map, not in the water

I managed to create a bathymetric map of the exit of the Cape St Francis canal. Notice that it’s off by a few metres. I was standing on the sandbank when I created this map, not in the water.

Here’s a video Robbie Alexander made showing how he mapped out one of his favourite spots…

How to access a bathymetric map

Once you’ve created a map, it’s saved to your history automatically.

To find a map, follow these steps:

  1. Open the app.
  2. Tap on History in the top menu.
    • you’re presented with a screen that shows all of your scans.
  3. Tap on a bathymetric scan.
    • A bathymetric scan is marked by three wave signals.
  4. You now have the option of scrolling through your scan, which allows you to see the depth and position of your scan.

If you tap and hold down on any of your scans, you’re presented with an option to delete a scan.

How to read a bathymetric map on the Deeper app

Once you’ve accessed one of your bathymetric maps from the history option, you’re greeted with the split screen that the app uses for creating this sort of map.

You’ll notice a play button in the top left corner. You’ll also notice an orange slider at the bottom of the screen, to the right.

If you press the play button, an optional slider appears that allows you to speed up or slow down the historical scan.

You’ll notice that, while you’re playing or sliding the scan, the icon representing the Deeper on the left of the screen moves while the sonar signal rolls over the screen.

If your scan shows a nice hole, ridge or other structure, stop playing the scan and check where the Deeper icon is on the map. The next time you visit the same spot, cast the Deeper out at the spot you’ve made a mental note of and see if there aren’t any fish hanging around.

This bathymetric map of the the St Francis canal can be played by pressing the play button, or by sliding the orange slider at the bottom

This bathymetric map of the the St Francis canal can be played by pressing the play button, or by sliding the orange slider at the bottom.

Is the bathymetric map accurate?

The Deeper contains a GPS. In order for the Deeper Pro Plus to create a bathymetric map, it works alongside your mobile device’s GPS.

You might notice that a bathymetric scan history is off by a few metres. I found that a scan I performed turned out to end a few metres away from where I was standing on a sandbank doing the scan. You’ll have to make up for this defect by using common sense.

The calendar

The calendar shows you lunar phases. For those who swear by this technique, this is a welcome addition.

Inside the calendar you’re presented with a month view calendar. You’ll notice plenty of orange dots. The more dots, the better the fishing is supposed to be on that day.

Tap on a day and the app shows you a four day view with moon phases and hourly activity.

GPS enabled devices show you information for your current location.

Like I said, if you fish by moon phase, you’ll most probably love this function.

How to access the calendar

To enter the calendar, do the following:

  1. Open the app.
  2. Tap on Calendar in the top menu, top left.

The camera

The app comes with a built-in camera.

When you click on it, it opens your phone’s camera, ready to take a picture.

If you want to keep the picture, tap on the check mark in the top right corner. If you want to discard of the picture, tap on the cross in the top left corner.

If you decide to keep the picture and tap on the check mark, a window opens up where you’re presented with the opportunity to add a caption and comments to the photo.

What I love about this feature is that the app automatically adds GPS coordinates, time, date and weather. This is a phenomenal way to keep track of your catches and build up a database of successful fishing days.

To access the photo you’ve taken, tap on Notes, then on the list icon.

How to access the Deeper app’s camera
  1. Open the app.
  2. Tap on Camera in the top menu.


The weather function shows what the weather is like where you are. It shows temperature (high and low), wind direction and speed, humidity, sunrise, sunset, moon-rise, moon-set, moon phase and air pressure. It also shows a four day forecast, albeit scant.

You can also add a point of interest and check the weather for it. This function needs some work. I couldn’t figure out how to add a point of interest. I moved the cursor to East London to add it as a favourite, but there was no save option. I searched for East London and nothing came up.

This part of the app either needs more work, or you’re better off using a stand-alone weather app.

How to access the Deeper app’s weather function
  1. Open the app.
  2. Tap on Weather in the top menu.

The Deeper app's weather screen

The Deeper app’s weather screen.


The notes function ties in with the camera. When you take a note, you’re given the option to add a picture. You cannot add notes to future days, only the current day or past dates. The idea with the notes function is to log fishing conditions and catches. Think fishing log, not Dear Diary.

How to access the Deeper app’s notes function
  1. Open the app.
  2. Tap on Notes in the top menu.
How to log a catch
  1. Open the app.
  2. Tap on notes in the top menu.
  3. Tap on today’s date, or a past date. Or tap on the plus icon in the top right of the app’s screen.
  4. Add a caption, a photo and some comments.
  5. Tap on Save.

The notes function is closely tied to the camera function. If you’re going to keep a fishing diary, might as well take pics of the fish you’re catching.

Scan history

The Deeper records all of your scans and stores it for later access.

This is a great feature, since it’s not possible to keep your eyes on your mobile phone at all times.

How to access scan history

If you think you may have missed important information, access the scan history as follows:

  1. Tap on the History button in the top menu of the app.
  2. Choose from one of the history options.
  3. Press the play button or scroll through the chart with the slider at the bottom of the screen.

You’ll notice that your history includes the date and time of scan. It also tries to give you an accurate location, but if you’re out in the middle of nowhere, chances are it won’t do such a good job.

The great thing about the Deeper’s scan history function is that you have access to an unlimited amount of history, at no cost.


The Deeper app offers you a slew of settings. A quick look inside the Settings option in the top menu reveals units, brightness, offline map settings, Deeper sonar simulation, night fishing mode, frequency settings and alarms, including a fish alarm and depth alarm.

The user manual is also accessed through the settings window, as well as options to export to and import from Google Drive (Android only).

How to log out of the Deeper app

You might want to log out of the Deeper app for some reason. Follow these steps to do so:

  1. Enter the app on your phone.
  2. Tap on Settings.
  3. Tap on Account.
  4. Tap on the Logout button.

Can you use the Deeper sonar without the app?

It’s not possible to use the Deeper sonar device without the Deeper app.

Can you use the Deeper app without the sonar?

You can use any of the built-in functions—calendar, camera, notes and other functions—without connecting to the Deeper sonar device.

You can even access your scan history.

Keep in mind that some of these functions require data or Wi-Fi.

To connect the Deeper sonar to the Deeper app does not require data, even though it connects through Wi-Fi.

Does the Deeper app drain your phone’s battery?

I’m on a Huawei P8 Lite. It’s not known for great battery life. When I tested the bathymetric function, the phone’s battery level was well above 90 per cent. I started using the Deeper at about 11:54 am and stopped using it around 12:22 am. This drained about 35 per cent of my phone’s battery.

So yes, this tool puts a lot of pressure on your battery.

Back up your data to Google Drive

Only available for Android devices.

It’s simple to back up your data to Google drive.

First off, you need a Google account. If you don’t have one, create one. It’s free and gives you 15Gb of storage, to name but one benefit.

If you have a Google account and it’s set up on your Android phone (it should be, since it streamlines workflow tremendously), follow these steps to back up your data to Drive:

  1. Open the app.
  2. Tap on Settings in the top menu.
  3. Scroll down and tap on Export to Google Drive.
    • You’re told to wait a bit…
  4. Allow Deeper access to your Google account (you can revoke this at a later stage if you wish).
    • Once you’ve allowed access, the screen goes back to Settings.
  5. Tap on Export to Google Drive again.
    • Wait for the export to finish.
  6. Open Google Drive at
  7. Your data, along with pictures, are now stored in your Drive, inside a folder called Deeper Application Backup.

The import process is as simple, once your Google account is set up on your Android device.

Optional: join the Deeper Hero community

Deeper offers their users a place to share catches and fishing info. They call it the Hero community. It’s entirely optional, but I went ahead and created an account. Here’s how:

  1. Visit
  2. Fill in all required fields (and more, if you wish).
  3. Click the submit button.

Here’s the interesting bit. These guys don’t just allow you to join the community. Once you click the submit button, you’d expect another page to open with your profile all nicely set up.


You’re directed to a page with this message: “Thank you for your application, we will get back to you as soon as possible.”

The message you're shown after registering for the Deeper Heroes section

The message you’re shown after registering for the Deeper Heroes section.

This is followed by an email with the following message:

Hello angler!

We’re super glad to receive your application for the membership in our pro-staff community. It’s an honour for us to know that you’re excited and willing to share your experience with us and participate in this amazing cooperation!

However, we’ll ask you to give us some time to review your insane profile. Due to an extremely high number of applicants, the process of reviewing the details might take approximately 1 week.

Hope you stay excited about Heroes program till we get back to you! Please be patient and keep on fishing. Tight lines!

Sincerely yours,

Deeper team.

These okes are either highly popular, or faking popularity really well.

In conclusion

The Deeper Pro Plus fish finder is an excellent device. It does a fine job of showing you what’s happening beneath the surface of your favourite fishing spot.

Not having to jump through hoops to connect your phone with the sonar makes using the Deeper fish finder a joy.

The notes functions is great for creating a useful fishing diary.

The bathymetric map creation function, in my opinion, is the highlight of the Deeper fish finder. This is an invaluable tool for the fisherman who wants to know exactly where to cast his bait the next time he goes fishing. It takes time to map a fishing spot, but it’s time well spent.

Furthermore, it’s a rugged little tool. Don’t play tennis with it, but considering what it offers, it’s tough enough to offer you years of fish finding.

There are three minor irritations: it takes over your Wi-Fi if you connect to it, leaving your home Wi-Fi without a fighting chance; it connects to Bluetooth when you open the app, despite it not needing Bluetooth, and the built in map (not the bathymetric mapping function, mind you) is rather useless.

Despite those irritations, the Deeper stands out as a must-have tool for those fishermen who wish to up their game considerably.

I highly recommend getting the Deeper Pro or Deeper Pro Plus.

Buy Deeper Pro


  • Deeper Pro – R4,899
  • Deeper Pro Plus – R5,299

Sonar reading material


About Author

Before making a purchase, you gather as much information as you can about what it is you're buying. You make sure you know exactly what you're spending your cash on. The world wide web, as wonderful as it is, often falls short of providing enough data to help you make an informed decision. How do you know whether you can trust online reviews? How can you be sure that you're not wasting your money on a product that, at face value, looks great, but once you start using it, turns out to be junk? That's where I come in. I've been involved in the world wide web since 2006. I'm a qualified digital marketer, driven to create trustworthy content. However, I'm also an avid outdoorsman; a light tackle lure fishing fanatic (I even make my own lures). I spend a lot of time hunting for fish (at least three times a week). This puts me in the ideal position to test all sorts of tools geared towards making your outdoor adventures as pleasant as possible. And that's exactly what I do. I test gear. But I don't just skim the surface. I dig into a product to give you all the information, so that, when you purchase online, you do so with confidence. I qualified as a toolmaker many moons ago. I spent years making all sorts of wonderful contraptions. This gave me a love for the technical side of things. Working with metals, plastics and other materials gave me an understanding of how things work, why they work, and, if they don't work, why they don't work. This technical background allows me to give you a deeply informed opinion about the outdoor products I test. Mantality is an excellent online shop. I love buying products from them. They do every step of the online purchasing journey exceptionally well. I can't possibly offer you a better online buying experience. What I can do, is give you no nonsense, genuine, in depth reviews of products available on Mantality. With Mantality's commitment to the perfect online shopping experience and my obsession with detail, your buying journey becomes a lot easier. Rest assured, if I give a product a thumbs up, you can buy it with confidence. Thanks for stopping by and enjoy the adventure!


  1. A little more than 2 years past, I found your review to be full of information and very helpful! I’m in the States (Southwest Ohio) and fish a variety of waters, e.g. ponds, lakes, rivers, creeks, etc., and chase mostly the Bass family and Catfish; and Saugeye. Walleye and Muskie. I mostly fish from shore but occasionally get out in a Jon Boat or Canoe. There are a lot of waters I know well, only because I’ve fished them for years. Others I’d rather not spend “a few years” getting to know like the back of my hand. Even the spots I know well, using the fish finder feature will be key on whether a particular spot holds fish, or if moving on is better. Talk about a time saver! Nothing worse than unpacking your gear and getting lines wet when nothing’s there. I’ve been in the market for a castable fishfinder/mapper for a few years and have always leaned toward the Deeper. I appreciate the detailed pros and cons and best uses. Looks like I’ll be getting one soon.

    Go Springboks!

    Cheers, Eric aka EStrong

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