Water Princess

Water Princess is a princess of an, as of yet, unknown kingdom within Ooo. She plays a minor role in the Issue 4 of the Adventure Time Comic where at the request of Princess Bubblegum she uses her powers to create a lake for Desert Princess' new kingdom in Ooo.

Appearance
She has long hair that seems to resemble seaweed. The base of her gown looks like a mermaids tail, and has bare feet poking out from the bottom of her dress. She also wears a sea urchin like tiara with pearls to show her royal status. She has very pale blue skin.

Princess Bubblegum
The two princesses seem to know each other and have a friendly relationship. It was upon Princess Bubblegum's request that she used her powers to make a lake for Desert Princess.

Lamprey Princess
The two princesses seem to know each other having a friendly relationship. Lamprey Princess was next to her when she was creating the lake for Desert Princess.

Choose Goose
She also seems to be on good terms with Choose Goose since the two where seen happily playing in Desert Princess's new lake.