Waterfall Cave (Japanese: たきつぼのどうくつ Basin Cave) is a dungeon in Mystery Dungeon: Explorers of Time and Explorers of Darkness and Mystery Dungeon: Explorers of Sky. It has eight floors and is unlocked after beating Drowzee on Mt. Bristle, and performing sentry duty at the Wigglytuff Guild. This is the first dungeon to have shops in Mystery Dungeon: Explorers of Time and Explorers of Darkness and Mystery Dungeon: Explorers of Sky.
On the first visit, the hero and the partner are asked by Wigglytuff to explore the dungeon. Upon reaching the bottom, they stumble into in an alcove filled with gems and a giant gem is at the back. The partner wants to take the gem back to the guild but finds it difficult to remove. It is at this point when the hero experiences another dizzy spell and sees an image of the past. A Pokémon had pushed the gem and had accidentally set off a trap that caused a flood to wash it away. Unfortunately, the hero is too late to warn the partner Pokémon as he/she pushes the gem and triggered the flood. However, they are flushed away to the Hot Springs where they first meet Torkoal.