The Eagle River is a tributary of the Wisconsin River in northeastern Wisconsin in the United States. Via the Wisconsin River, it is part of the watershed of the Mississippi River, draining an area of 181.7 square miles (470.6 km²) in the state's Northern Highland region. The river flows for much of its length through a series of lakes; the network of 28 lakes in the Eagle River's watershed is locally claimed to be the "world's largest chain of inland freshwater lakes."