Koj is a small island in the Summer Isles. Koj separates the Smiling Sea to its southeast from the Summer Sea to its west. Southeast of Koj are the Isle of Birds and Omboru, while Lotus Port on Walano is to its north. To the south and southeast are the Isle of Love and the Singing Stones.
Despite not being one of the three large main islands in the chain, three-quarters of all swan ships in the Summer Isles are made by the famed shipbuilders of Koj. Malthar the Mapmaker, a prince of Koj, is regarded as having been the greatest shipbuilder from the isles. Adventurers from Koj are rumored to have explored much of Sothoryos and the Sunset Sea. The Princes of Koj reside at the Pearl Palace.