Many years ago I took my scout troop to a local pool one night for a swim test. I required the boys to swim nonstop, fully clothed for 100 yards before they could even get into a canoe on a lake for a ride. I got them at the deep end of the pool and told them to jump in and swim two full laps. One boy who was new jumped in and went straight to the bottom. He couldn't swim a stroke, but was ashamed to admit so to me or his peers. We fished him out and I assigned one of my Eagle Scouts to teach him to swim. Within a month he was going off the low board and scaring his mom as she thought he was going to drown. He is now a successful businessman and is taking his kids canoeing.
I am glad that you fished him out. (seems the responsbile thing to do for a scout leader)