Merman Combat is a fighting style used by the merfolk. It is used underwater and involves manipulating the water with their hands as if it were something tangible to use for long ranged attacks. It is the merfolk equivalent of Fish-Man Jujutsu.
Ultramarine (ウルトラマリン,Urutoramarin?): Used by Neptune and Fukaboshi, the user grabs the water with their hands, similar to Mizugokoro, and then hurls it forward in a mighty, extremely large torrent that blasts away his opponents with great force. "Ultramarine" usually refers to a shade of blue and got its name from "ultramarinus", literally meaning "beyond the sea". In One Piece: Gigant Battle! 2 New World, Neptune condenses the water in the atmosphere into his hands as a sphere and launches it forward as a massive torrent.