Learning to swim is all well and good, but knowing personally 2 men from my youth who were very powerful swimmers yet both died in the Irish sea due to hypothermia, sets things in perspective...if it's inland waterways, swimming is good, if it's costal and you don't get help fast,being able to swim is not necessarily an advantage, when afloat you should always wear a life jacket note not a bouancy aid but a LIFE JACKET! ( hypothermia may still get you though)
I have done quite a few boating courses and I remember well one instructor telling me to always wear a life jacket in the sea, "cause there's no way you're swimming to shore from 10 miles out and if hypothermia does get you then with a life jacket at least we can retrieve your body!" That shocked me, but I got the point.