As a kid playing a little shinney on a local river one of my buds younger brother fell through the ice retrieving a puck. Lake falls are pretty meh (I fell through a few times as a kid). Rivers, not so much...he fell in and was gone, just like that.
I started my swim lessons at 50 from the scratch. After changing few coaches and two years later I can swim pretty good now. Please pick a younger person as your coach they have lot of appetite for teaching than older guys. I wasted a year of time using a person who taught me nothing. As someone mentioned, swimming involves lot of physics, how you take advantage of the water pressure on your body, as well as breathing technique. From my personal experience it not late for learning any skills. I took ski lessons at 44 and learned it. Go for it, I am in great shape now than any time before in my life. Good luck. Lot Sent from my iPhone using FerrariChat