Purity Forest (Japanese: きよらかな もり Pure Forest) is a post-game dungeon accessible in both Red and Blue Rescue Team. It contains 99 Floors, with Celebi resting at the final floor. This dungeon can be accessed after clearing Pitfall Valley and acquiring the Friend Area Sky Blue Plains. This dungeon is arguably the hardest dungeon, as your level and IQ will be reset to their initial settings (which is level 1 and initial skills respectively, unless the player leaves the dungeon), you cannot bring items, currency nor friends, and is a dungeon purely based on luck. Any items or currency that are brought along will be lost permanently.
Pokémon cannot be recruited in this dungeon, items have a 5% chance to be sticky, and all floors have the heavy darkness effect.
Upon reaching Celebi on the last floor, it will instantly want to join your team, and you are given the option to let it join. If chosen to join, Celebi will dance happily and you will get to name the newly recruited Pokémon. You will also obtain the Friend Area Healing Forest. If chosen not to join, Celebi will leave, disappointed.
- This dungeon is called "the Ultimate Dungeon" in Issue #21 of Pokémon News.