Or at least drown-proofing.

The problem with knowing how to swim is that you then think you know how to rescue people in the water. Unless you've been trained for this - you don't. A drowning person isn't thinking; they'll latch on and drag you down too. At a minimum, swim out with something, like a towel that they can grab without you getting into grab range yourself, And if they to manage to grab you, swim downwards to get them to let go.

I never met my paternal grandfather because he drowned - trying to save someone.