The Fever River is a river in the Neck in the south of the north. Moat Cailin lies less than twenty miles from its headwaters. The mouth of the river opens to the Saltspear.
Victarion Greyjoy sails the Iron Fleet up the Fever River and takes Moat Cailin, which lies nearby.
Victarion sails from the Fever River, where the Iron Fleet had beached itself while holding Moat Cailin, to the kingsmoot on Old Wyk.
The Ryswells and Dustins surprise the remaining ironmen on the Fever River and manage to burn their ten longships.
The Fever River may be a reference by George R. R. Martin to his novel Fevre Dream, which is set on the Mississippi River.