Crystal Cave (Japanese: すいしょうのどうくつ Crystal Cave) is a dungeon in Pokémon Mystery Dungeon: Explorers of Time and Explorers of Darkness and Pokémon Mystery Dungeon: Explorers of Sky. It has 11 floors. After the 11th floor, players must solve a puzzle to get to Crystal Crossing. To solve the puzzle, the player must turn all the crystals blue. It is unlocked the day after the player beats Mesprit in the Quicksand Cave dungeon.
You'll encounter the same traps from Quicksand Cave.
Poké encountered here is found in packs of 2-113. There seems to be no connection to items and floor.