The Yarne is the only major river flowing across Comack Island. It has two tributaries. The Western Yarne flows from the mountains bordering the Badlands eastwards past the village of Highwatch. The Southern Yarne begins in the south of the island and takes a meandering path northwards until it meets the Western Yarne in the town of Stitch. The combined flow of the two tributaries flows north out of Stitch, before reaching Lockenport City.
Between Stitch and Lockenport, the Yarne is a wide, easily navigable river and there is constant boat traffic both upstream and down. The Western and Southern Yarne can be partially traveled by boat, but both contain sections with hazards such as rapids and thus goods are not usually transported along the two tributaries.
The Yarne boat race is an annual traditional. Participants race from a point approximately half-way along the Western Yarne and the winner is the first boat to reach Stitch. In recent years, the race has gained a reputation for dirty tricks, but this has only made it more popular amongst the spectators who line the banks to watch.
There is currently a group of bandits plaguing a stretch of river southwest of Stitch, where the banks are steep and the river flows quite rapidly. The bandits tend to waylay travelers by capsizing their vessels and then stealing any goods they can reach, while the rightful owners are carried away by the river.