Epsilon Thalassus is one of the planets the Hero visits in Cluck of the Dark Side. He has to descend down to Epsilon in order to retrieve the Blade of Revolution. The planet is located on a galactic arm close to the Norma Galactic Arm in the Milky Way.
You can watch a tour of the planet here.
The planet's surface is mostly dominated by large oceans, as the Narrator says that 98% of it's surface is covered with water. That means the other 2% is land. Based off of the glow, and off of that liquid water can exist on it, the planet might have an atmosphere and temperatures similar to those seen on Earth. It also has a weather system, as clouds are visible.
There are different kinds of aquatic life that populate Epsilon, such as giant Squids, Jellyfishes, and very likely other species too. Earth has similar aquatic life, which makes both planets very similar to each other.