Atlantis is an underwater city in Chima. The tribes consist of Piranha, Sharks, Squid, and Lobsters. They also have Water Chi. Atlantis is the main setting in the Atlantis story arc.
- Posideum: The king of Atlantis.
- Percy: Posideum's son and the prince.
- Pyon: A fierce piranha warrior.
- Pierra: A female piranha warrior.
- Squidbeak: The leader of the Squids.
- Squilox: A large squid warrior.
- Sqallie: Squidbeak's older daughter.
- Squella: Squidbeak's younger daughter.
- Baroxx: A barracuda, he is a warrior and guardian of the Water Chi
- Raxia: A ray, he is a scientist researching Water Chi
- Hector: A Hammerhead shark who is a ship builder, he hates Pirates