I really wish I had seen this thread at the beginning instead of the end as I might have been able to ease your mind a bit. I have found my snakes, both kings and corns, completely submerged in their water bowls for extended periods of time (hours), sometimes all knotted up, sometimes just in a normal coiled position, I've seen it before a shed and after a shed. It's just something they want to do. I'm sure they come up for air when they need to, but duck back down when I come close as if they are trying to hide from me. I just let them enjoy their bath unless it's dinner time and I need to clean their tub, weigh them and feed them. And 9 times out of 10, they're right back in the water dish, whether they ate their dinner or not, and have a look that screams "Will you just leave me alone!"