I admit I'd be pretty nervous to even consider something like this.
BUT, I have a large female normal ball python who snorkels in her water dish every time I fill it. She submerges her entire head and neck, then blows bubble out of her nose. The first few times it happened, I thought she was going to drown! I was afraid she went to get a drink and fell in or something? I don't know but it freaked me out pretty badly. Then after a little while, I realized she was doing it on purpose. She zips right to her clean, full water bowl and spends the next 15 or 20 minutes snorkeling. She does it every single time I clean and fill her dish, so I know she enjoys it. I bet she'd swim if I had the nerve to let her try.
Gale