The other lesson repeatedly drummed into us by our mother is to never jump into water without checking it first. There are also many stories of people becoming paralysed after diving into water.

The last lesson is to be careful of people drowning. If you get too close they can grab onto you, pulling you underwater and cause you to drown. If someone is drowning, either grab them from behind, or use a stick or I guess be at a distance where they can't pull you under.

One last lesson I learnt as a kid was to stay clear of dogs swimming - if they get too close they can claw you while doggy paddling.

This is no longer about the original topic, instead I'm going off on a tangent inspired by your comment.

I'm curious if you could do something with this short comment: I only really felt I "got" swimming when I felt as comfortable under as above water, and more importantly, dynamically mixing the two. As long as my swimming mode, in the early days. concentrated on staying above water, from today's point of view it was maybe the quarter of the way to swimming safely at most.

Staying completely submerged during swimming while you don't need air saves a lot of energy, you can just swim through big ocean waves without being bothered, etc. Also, being used to spending most of the time completely submerged makes it easier to deal with when it happens accidentally.

A swimmer trying to keep their head above the water at all times, I don't think that this works very well unless conditions (of oneself too) are ideal or close to it.

Even then, I think I heard it in one American astronaut's interview about his training, additional high-stress training under water that you can't usually get because it has to be well managed by other people including safety divers, would still be missing from a normal person's experience. As a new diver I got into a very mild panic only once, fortunately close enough to shore (California kelp forests off a Monterey beach), and it was bad enough. I would not want to be caught in some eddy unable to surface with mounting alarm. Still, being comfortable doing most of the swimming submerged already is a huge step up from head-above-water mode swimming.

One should also have reviewed the local water currents and what to do when one is caught, but that's another issue.