Manta Ray Surfing
From the Super Mario Wiki
Manta Ray Surfing, more commonly referred to as Ray Surfing, is one of the four minigames from Super Mario Galaxy, along with Bob-omb Blasting, Bubble Blowing, and Star Ball Rolling. Ray Surfing appears in two galaxies, Loopdeeloop Galaxy and Loopdeeswoop Galaxy. In the Loopdeeloop Galaxy, the player is taught how to ray surf by Coach. After he collects the galaxy's power star, Mario or Luigi (depending on who is being played) is considered a champion surfer. In both galaxies, the player must surf on a large Manta Ray, using it as a surf board to traverse a course made up of water.
The player must point the at the screen and twist it to the left or the right to go in said directions. The is to accelerate and flicking the remote allows Mario and the Ray to jump. Turning too much will make the manta ray fall of the stage, resulting in losing a life.