The title of this article is conjectural; an official name for the article's subject has not been found, so it has been given a fitting title by the editors. If an official name appears, it is requested that the article should either have a reference added or be moved to the correct name.
A Submarine Guy.
Submarine Guys are invincible Shy Guys that drive single-seated submarines. They patrol the ocean waters surrounding Yoshi's Island, and fire torpedoes (similar in design to Torpedo Teds) at intruders.