Irrson has a single island that does not seem natural to the world: Crais Island, a towering black rock edifice with an immense stronghold, long abandoned, carved into the stone. Who built the place, who raised up the unnatural but enduring mass of rock, is unknown, but it goes back far beyond the memories of the Salkeyri. Irrson was known to be in somewhat close proximity to Ubel, another world in Wild Space.