Skull Island, also known as Skull Isle, is the northernmost of the Basilisk Isles. It is located in the Summer Sea north of Zamettar in Sothoryos. The small isle is windswept and uninhabited.
Many of corsairs of the Basilisks decorate the hulls and maps of their ships with severed heads. When the flesh has rotted off them, the corsairs replace the heads with fresh ones, while the bare skulls are delivered to Skull Isle as an offering to some dark god. The shores of the island are lined with skulls.