Manu-kura was a famous warrior in the Tuamotuan version of the Rata cycle of Polynesian mythology. His home was in the ocean.
He married Pupura-to-te-tai, the daughter of Puna, king of the Underworld. When Rata met him, they had a contest of magic girdles that Rata won, claiming Pupura as his prize. He took her to his home, where she stayed while he continued his quest to avenge his father.
References
Manu-kura Wikipedia(Text) CC BY-SA