In fall of 1967, I was going thru Navy boot camp.(Co.001 Nav TR Ctr, Orlando FL). We had basic swimming test, wasn’t much of a test. Jump in deep end of a pool, tread water 10 mins, swim length of the pool and back and you passed.
We had 1 black guy in our company and he did not want to get in the water, so the DI assisted him in getting in. He sank right to the bottom like a stone, he was on the bottom maybe 15 or 20 seconds and we all realized he was not coming back up. Someone put the rescue pole down and pulled him back up and out.
He was out of the Navy the next day. Seems the USN has some rule that if you cant swim, you cant be a sailor.
I had never seen anything like that. If I want to get to the bottom of a pool, I have to make the effort to swim down there.