Lake Dunmore spans the towns of Salisbury and Leicester and has a surface area of 985 acres. It is over 3 miles long (oriented north-south) and up to 1 mile wide. The primary source of water is Sucker Brook, which rises in the adjacent Moosalamoo National Recreation Area of the Green Mountain National Forest. The lake is drained by Leicester River, a tributary to Otter Creek, which in turn empties into Lake Champlain.

Branbury State Park occupies 69 acres of the eastern shore and offers a sandy beach, canoe rentals, and campsites. VT-53 follows the eastern and northern shores of the lake. Most of the shoreline is privately owned.

Although a natural lake is formed by glaciation, the water level is controlled by a small dam. In addition, Sucker Brook is part of a hydroelectricity project connecting Silver Lake and Sugar Hill Reservoir via Sucker Brook and is operated by Green Mountain Power.

Fern Lake lies to the south of Lake Dunmore.

Lake Dunmore (985 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.