You’ll need to think fast here, although not so fast that you don’t first consider the dangers involved to you, the would-be hero.
Your natural instinct may be to dive head-first into the water and drag the thrashing drowner to safety, but you’d be a tad premature and endangering your own life…
Warning: Only ever enter the water as a last resort
If there’s a stick or pole to hand, hold it out and suggest that the swimmer (well, drowner) hangs on as you haul him hack to safety. If someone’s thoughtfully hung a life ring on the end of a rope nearby, toss that instead and haul him hack to dry land. Either way, make sure you’re secure on the sidelines as you pull, so as not to get yanked in yourself. Finally, if there happens to be a boat on-hand, row out to the victim before employing the stick or ring methods.
If this stretch of water is lacking long sticks, floating rings, and useful boats, the only option is to enter the water-But Only If You’re A Trained lifeguard. If you’re not, you’ve officially done all you can fuor this person and should now call 911 for assistance and wait. Unless you’re trained, you should under no circumstances enter the water even if the drowning person is a member of your family or a close friend who owes you money.
The danger is that in their blind panic, drowning people often drag their rescuer under the water as they struggle, very selfishly putting two lives at risk. A trained lifeguard would know that it’s vital to talk to the victim as he approaches and to tell him he’s about to help him back to shore. That would calm him down and allow the rescuer to hook his arm over the victim’s chest from behind. He could then tell him to relax and float on his back to make things easier, as he used his free arm to sidestroke them both hack to safety.
If the victim does drag this trained hero down, he’d know to swim down further under the water, aware that the victim will fight to return to the surface and thus set him free. Once back on shore, the expert would know to check the victim’s airway, breathing and circulation, and how to administer CPR, if required. He’d also know to treat them with extreme care throughout so as not to exacerbate any injuries already sustained.
That’s what he’d do. You, of course, are not trained so should stand helplessly on the river bank and watch as the victim disappears under the water.
Warning: this is based On relatively still waters rather than any stretch with dangerous undercurrents. Diving into the water is a risky business and you could lose your life.