Sensuikan Heihō

Submarine Guys are invincible Shy Guys that drive one-man submarines. They patrol the ocean waters surrounding Yoshi's Island, and fire torpedoes (similar in design to Torpedo Teds) at intruders.

Submarine Guys only appear in the game Yoshi's Story and even then only in the third part of Stage 5-1: Lots o' Jellyfish.