Sootopolis Gym is located in the underwater city of Sootopolis, which is part of the Hoenn region in the Pokémon world. This gym specializes in Water-type Pokémon, making it a challenging place for trainers who are not prepared for aquatic battles. The gym leader is Wallace, known for his elegant battling style and strong Water-type Pokémon. To enter the gym, trainers must navigate through a series of puzzles involving water and ice. Once inside, they face various trainers before challenging Wallace himself. Defeating him earns the Rain Badge, which allows trainers to use the move Surf outside of battle.