Thallassa is a planet in the Unknown Regions of space. A water planet rich in sea life and sparse in land mass. Many species thrive around the tropical equator. Most species assume an amphibious existence living a double life in the sea and on the small patches of land. The prominent sentient species, know as Thallassans, developed in the water but eventually grew accustomed to living on land. The other sentient species on the planet were known as the Delphi, who were solely aquatic.