Etheenia was a location visited by Enterprise NX-01 during its historic mission of exploration in the 22nd century. In 2152, while stranded on a moon with an increasingly rising temperature with an Arkonian named Zho'Kaan, Commander Charles Tucker III reminisced about some of the experiences he had while on Enterprise, including diving in the ice caves of Etheenia. (ENT: "Dawn") The Star Trek Encyclopedia (4th ed., vol. 1, p. 252) identified Etheenia as a planet.