Here's a character that me and cyberdragon5 on DA own, named Ralarth. His belly contains an ocean's worth of water, all put into a pocket-dimension like space in his belly. He gets all of this from accidentally swallowing the pearl that most eastern dragons have that gives them their powers. For this reason, he is known as the mobile ocean. He's proud about his belly, even if it does weigh him down a bit.

On DA: http://iminsftw.deviantart.com/art/Ralarth-the-Mobile-Ocean-579963483
Cyber's entry: http://cyberdragon5.deviantart.com/art/Ralarth-The-Mobile-Ocean-By-Iminsftw-579975589
Ralarth's anthro form: http://leo-the-lion98.deviantart.com/art/Art-Trade-580017360