However, it's possible you're thinking of a different location:
* Thunder Cave: This location appears in several Mystery Dungeon games, including Red Rescue Team, Blue Rescue Team, Super Mystery Dungeon, and Explorers of Sky. It's often a difficult dungeon with electric-type Pokemon.
* Thunder Plateau: This location is featured in Explorers of Time, Darkness, and Sky. It's a challenging dungeon that includes the Thunder Fang Pokémon, Raikou.
If you can give me more details about the specific game and the context of your question, I can help you figure out which location you're thinking of and how to reach it.