I agree with Kurt, I have a pretty good size water area in my enclosure. It is not very deep but I hear them splashing about all night long. I've seen them bounce in and bounce out as if its a game and I think they like it. Mine water area is very shallow as I said so I'm not sure if they would swim underneath or not but they do seem to enjoy having a water section in the tank. With that being said, I just had a water bowl in my smaller tank and they did just fine. So is it necessary...probably not. But it is fun to watch them play in the water.