|Location||Franconia Notch State Park, Grafton County, New Hampshire|
|Primary outflows||Cascade Brook|
|Basin countries||United States|
|Max. length||0.2 mi (0.32 km)|
|Max. width||0.1 mi (0.16 km)|
|Surface area||12.2 acres (49,000 m2)|
|Average depth||4 feet (1.2 m)|
|Max. depth||8 feet (2.4 m)|
|Surface elevation||2,730 ft (830 m)|
Lonesome Lake is a 12.2-acre (49,000 m2) water body located in Franconia Notch in the White Mountains of New Hampshire, south of Cannon Mountain. The lake is reachable by hiking trails from the Franconia Notch Parkway, including the Lafayette Place Campground, and takes approximately 2-3 hours. It features an Appalachian Mountain Club hut, which first opened in 1930, on its southwest shore.
The lake lies in the Merrimack River watershed. Its outlet, Cascade Brook, flows south over ledges and waterfalls to the Pemigewasset River near "The Basin" in Franconia Notch. The Pemigewasset in turn flows south to the Merrimack River, which reaches the Atlantic Ocean at Newburyport, Massachusetts.
- New Hampshire GRANIT database Archived August 3, 2013, at the Wayback Machine
- "Lonesome Lake Trail: A guide to one of Franconia Notch State Park's most cherished hikes – NH State Parks". blog.nhstateparks.org. Retrieved October 6, 2020.
- "New Hampshire's White Mountains: Lonesome Lake". www.visitwhitemountains.com. Retrieved October 6, 2020.
- "Lonesome Lake, Lincoln" (PDF). NH Fish & Game. Retrieved September 2, 2014.