No screaming, no frantic waving; a drowning person looks very much like they’re just swimming. And so you may look at the person next to you at the beach, seemingly having fun in the water, when in reality they’re seconds away from sinking.
I learned that the fastest way to find out if a person’s about to sink is to just ask them: “are you ok?” If they don’t answer, it means they’re drowning.
Another thing I learned is to not ask random people to teach you how to swim. They may look like they’re good at it, they may seem like they’re having a great time in the water, but you can never be sure what’s going on under the surface.