The Pirate Cave (海賊の洞窟, Kaizoku no dōkutsu), also called Underwater Cave (海底洞窟, Kaitei dōkutsu), is a cave located underwater, northeast of Kame House. It was once the secret base of a Pirate Crew which was quite advanced for its time.
Goku, Bulma and Krillin came here in search of a Dragon Ball (the Three-Star Ball) while followed by General Blue and his soldiers. The entrance to the harbor is a hallway covered with holes on the walls and buttons on the floor; if anyone touches one of the buttons, arrows will be shot from the walls. Past this, there is a lava trapdoor that Goku and the others almost fall into. To pass those trap, there is a secret passage that General Blue used, and which leads to the pond of a Giant Electric Eel.
In the harbor there are several ancient submarines and boats. Inside, the Pirate Robot guards the harbor. The pirate treasure rests deeper inside the cave, past all of the traps and a Treasure-Protecting God Statue. The cave later collapsed after the fight between Goku and General Blue. Hidden in a wall in the Pirate Cave, there is a grave of pirates of past generations that was revealed while the cave was collapsing; this place has the bones of the pirates' leader, and a large amount of treasure.
The Pirate Cave is a stage in Dragon Ball: Advanced Adventure, Dragon Ball: Revenge of King Piccolo, and Dragon Ball: Origins 2. In the bonus level 3-6 of Dragon Ball: Origins 2, Bulma goes in the underwater cave alone to find an octopus, because it contains a nutrient that make the skin beautiful. In the bonus level 3-7, Krillin returns to the cave in order to retrieve the pirates' treasure, but he is attacked there by the Pirate Robot. After defeating the Pirate Robot, Krillin unintentionally destroys the treasure by opening an explosive chest.
In Dragon Ball Z: Attack of the Saiyans, the Z Fighters visit the Pirate Cave once again in order to find the Five-Star Dragon Ball and resurrect Goku for the battle against the Saiyans. Enemies encountered here are Man-Fish, Big Crab, Wild Fish, Ship Ghost, Skull Robot, Pirate Robot, Pirate and Piratress, and the boss is a Giant Octopus similar to Octopapa. This Giant Octopus was told to guard the Dragon Ball by the Red Ribbon Army.
- One of the ancient ships resembled a WWII-era submarine. On that note, one of the guns that the pirates purportedly owned resembled the Vz. 61 "Skorpion".