Thoros-Beta
From Tardis Wiki, the free Doctor Who reference
Thoros Beta was a rocky planet inhabited by the Mentors and twin planet to Thoros Alpha. The many oceans of Thoros Beta were pinkish and the sky a greenish blue. It is also possible the mud was an orangey-brown colour (since Sil described Kiv's new body as mud coloured). There was also a large gas giant within sight of the surface. Most of the settlements were underground and located within caverns.
Seas on Thoros Beta included the Sea of Turmoil, the Sea of Despair and Longing and the Sea of Sorrows. One of the known islands was called Brak. (TV: Mindwarp)