One Piece: Season 1, Episode 526

Undersea Volcanic Eruption! Drifting to the Fish-Man Island!

The Flying Dutchman shows up and Vander Decken tells Wadatsumi to crush the Thousand Sunny, but then the Kraken beats Wadatsumi. The volcano erupts, and the pirates run from it. Surume jumps off a cliff and some big stones are about to crush them but Usopp stops them for a while with his new move Sargasso. But when they are celebrating their survival, a rock hit Surume's head, made it faints as they descending to the depth of the cliff. At the bottom of the cliff they find Fishman Island but when they are about to enter, they are stopped by a group of sea monsters and someone riding it.