Inis Olsang is a major island in the central-northern Skyre Islands, lying west of Inis Markul and north of Inis Muirin. Its position places it close to several of the narrow passages used for travel through the central archipelago. The best-known surface settlements are Gultne on the western side of the island and Obelmarge farther east.
The island is one of the Thegndoms of Asnorland and is traditionally associated with Cain Carthaigh of the Skyre Folk. As with the other settled islands, Asnor control is most visible around towns and coastal routes, while Skyre communities maintain their own territories and sacred places beyond those centers.
Inis Olsang also has an important subterranean geography. The Deep Gnome settlement of Dulthapplas lies in the Underdark beneath the island near Gultne. The Spatial Break means that reaching the settlement from the surface depends upon physical routes or exceptional forms of magic rather than ordinary long-range teleportation.