Tritonis

Triton (or Tritonis) was one of two major city states that made up the continent of Atlantis. The other was Poseidonis.

Background Information
On the parallel-universe of Earth-One, several thousands of years ago, groups of pilgrims settled in the greater Atlantean region establishing twelve distinctive communities, a few of which evolved into modern settlements, including Tritonis. Many believe that the original twelve settlements represented the twelve signs of the Zodiac.

After the continent of Atlantis sank, the city of Tritonis survived as an isolationist settlement beneath the seas. Those who survived the cataclysm adapted to their new marine environment.