From the Super Mario Wiki
Lots O'Jellyfish! is a submerged area in Yoshi's Story, level 5-1. Most of the level seems to be a large underwater maze filled with various fruit and dangerous creatures. As stated by the title of the level, Jellyfish are the most common enemy in the level. Several of these jellyfish have fruit floating inside their bodies, which can be can be eaten by Yoshi by sticking out his tounge. Parts of the level take place on an island (or islands) above the main level. The level also contains a area specifically for one enemy, the Snorkle Fish. This area is a small "X" shaped cave to make it easier for the snorkel snake to poke Yoshi. Other enemies include Submarine Guys, Spiny Fish, Teehee Butterflies, Blurps, and Sea Cacti.
To go any farther, the Yoshis had to brave the Ocean. They jumped in! They liked to swim, but the jellyfish's sting spoiled their fun. So they swam to dry land. Now they were almost to the end of the book!
Names in other languages
||Méduses à gogo