What misadventure did Douglas experience at the Y.M.C.A swimming pool?

The writer had to face an extremely traumatic experience at the Y.M.C.A pool. He used to go there to learn swimming. The pool was two feet at its shallow end and nine feet at the deep end. One day a strong big boy picked him up and threw him into the deepest part of the pool. He sank to the bottom, but he decided to fight back. He thought of going down to the bottom of the pool and hit the floor and jump up like a cork. He tried to jump and come up gradually. Unfortunately, he could not succeed. Thrice, he tried to jump up but he sank again. As fear had gripped him, all his efforts went in vain. He was nearly drowned. He tried to breathe but swallowed water. He lay there in complete peace without any sensation or the fear of death. But someone saved him.