L.H.
Your son is definitely old enough to be able to swim. I taught swimming lessons as a college student and, as long as the child is not grabbing the teacher in a throat hold terrified of the water, he can learn to swim at this age unassisted. In fact, you may have a short window of time to accomplish this before he knows to be afraid again. Then you will have a problem. I would recommend private lessons. The problem with having him take group lessons is that I would expect you have a bunch of kids in there who are afraid and who are therefore slowing his progress. They might also make him afraid later.
Call your local Y or wherever swimming lessons are offered and ask if any of the instructors give private lessons. It will cost you a little more money, but in the long run it may save you money if he just learns to swim.
If you are like me, a busy mom, it will also save you time. Why take him to a bunch of group lessons if he can learn to swim with 5-10 private lessons!
Good luck.
L.
Single mom to 2 1/2 year old girl.