North Cascades National Park is a national park of the United States in Washington. At more than 500,000 acres, it is the largest of the three National Park Service units that comprise the North Cascades National Park Complex. North Cascades National Park consists of a northern and southern section, bisected by the Skagit River that flows through the reservoirs of Ross Lake National Recreation Area. Lake Chelan National Recreation Area lies on the southern border of the south unit of the park.