A downloadable survival arena.
It is a round arena with a view of the edge of the island. There are mirrors on the edge of the arena that release Mirror Rick's in the final wave. Judging from the description on the downloadable content, it is possible that this supposed to be the island that West was shipwrecked on. If true, this mean that the island is home to the Thule Temple, where West found the Terror Mask locked in a sarcophagus.