Eight miles long with 28 miles of shoreline. This undeveloped lake is home to bald eagles, loons, and a variety of wildlife. The lake is open for swimming, kayaking, powerboats, sailboats, and paddleboards.

Harriman Reservoir, also known as Lake Whitingham, is the largest body of water located entirely within the state of Vermont. It is on the Deerfield River in the towns of Whitingham, Wilmington, and Readsboro. It was created in 1923 by the construction of the Harriman Dam, a hydroelectric facility named after Henry I. Harriman, a former president of the New England Power Company. The reservoir has a water surface area of 2,040 acres, a maximum depth of 180 feet, and a gross storage capacity of 117,300 acre-feet. It is one of ten hydroelectric dams impounding the Deerfield River.

The reservoir is a popular destination for boaters, swimmers, paddlers, and anglers. It offers views of the surrounding hills and forests, as well as glimpses of the submerged remains of old buildings and bridges that were flooded when the dam was built. The reservoir also has a unique concrete "glory hole" spillway, a freestanding conical drain that can be seen from the air or from a boat. The reservoir is part of the Molly Stark Byway, a scenic route that follows the path of General John Stark and his troops during the American Revolution.

Harriman Reservoir (2040 acres) is a site for the Vermont LoonWatch annual survey. Birders are encouraged to volunteer as often and whenever they are able. See Join LoonWatch for details.