My son Jon, a c5/6 complete swims on his back, and even does somersaults in the water now, and "dives into the pool either from his wheelchair or from the side. He uses plastic "waterproof" sandals to protect his feet from scraping on the bottom of the pool. But these sandals have also proven to be an effective flotation device keeping his feet near the surface! He began by using a life jacket, which gave his arms freedom to move. Please watch his videoSwimming for Quadriplegics - YouTube
, which also shows how he taught two c5/6 quads in INdia to swim in real time, w/in 15 min of seeing his demonstration. They were all using snorkel goggles to protect their eyes and nose, though one of them now prefers regular swim goggles and a nose clip. Have no fear, but enjoy - By the Way, the water in the video was unheated, though heated is better. They also used no incontinent devices, though US pools may be picky.