Etheenia

From Memory Alpha, the free Star Trek reference

Etheenia is a place known for its scenic ice caves, visited by the Enterprise between 2151 and 2152.

While trapped on a hostile moon with the Arkonian Zho'Kaan in 2152, Charles Tucker recounted diving in the ice caves of Etheenia as one of the experiences he never could have imagined if he had stayed on Earth. (ENT: "Dawn")