Catfish's Maw
From Zelda Wiki, the Zelda encyclopedia
This is the fifth dungeon in Link's Awakening. Link requires the Flippers to gain entrance to the dungeon. The main item in this dungeon is the Hookshot. After defeating the boss, Slime Eel, Link is awarded the Wind Marimba.
Miscellaneous
Catfish's Maw can be looked at as an early prototype or concept for the future dungeons: Inside Jabu-Jabu's Belly and Jabu Jabu's Belly.