Turnback Cave (Japanese: 戻りの洞窟Returning Cave) is a maze-like cave filled with dense fog which is home to the Legendary PokémonGiratina. Turnback Cave is located at the north-central region of Sendoff Spring, which itself may only be accessed through the Spring Path.
When a player exits a room, the next will be randomly chosen from a selection of possible rooms. If the player walks out the door through which they entered a room, they will return to the entrance room; from the entrance room, the player can exit to Sendoff Spring. If the player navigates 30 rooms without finding the third pillar, the next door returns them to the entrance room. Escape Ropes and Dig cannot be used to escape. The inscription in the pillar at the entrance room reads:
...Past three pillars...to the sleeping... ...before 30 is surpassed...
After the player has found three pillar rooms, the next room will be Giratina's room. In Pokémon Platinum, Giratina will only be in this room if the player did not catch it in the Distortion World. If Giratina is not present, there will be an item each time it is reached, with the item depending on the number of rooms the player navigated to reach it: a Reaper Cloth if they reach it in 3 rooms, a Rare Bone if they reach it in 4 to 15, and a Stardust if they reach it in 16 to 30. In Pokémon Platinum, after catching Giratina, there will also be a portal to the Distortion World, where the player can obtain the Griseous Orb.
When the player reaches a pillar and examines it two numbers will appear: the top number indicates which pillar the player is looking at, and the bottom indicates how many rooms the player passed through on the way to it.
Before being able to obtain the item at the end of the cave, the player must first catch or defeat Giratina. In Pokémon Platinum, if the player defeated Giratina in the Distortion World, they must defeat or catch it here and traverse through the cave again in order to be able to obtain items here.
Turnback Cave and the Distortion World may draw some inspiration from the Japanese underworld, Yomi. Giratina itself can be seen as a parallel to the kami Izanami.
Turnback Cave shares its music with that of the Old Chateau. However, in Pokémon Diamond and Pearl, the version of the track used in Turnback Cave and the surrounding areas is noticeably lacking certain soundfonts. Interestingly, this variation is not recognized as a separate track in the game's audio files and the normal variation of the track is used in Pokémon Platinum, suggesting the difference between the versions was unintentional.