Lost Lake, Mountain lake in Hood River County, United States.

Lost Lake is a natural lake in Mount Hood National Forest, 10.1 miles northwest of Mount Hood in Hood River County, Oregon. It is bounded east by 4,468-foot Lost Lake Butte and southwest by 4,556-foot Preachers Peak. Fed by three unnamed intermittent creeks and Inlet Creek, it drains at the north tip into Lake Branch Hood River. At 167 feet deep, it is the second-deepest lake in the forest after Wahtum Lake.

Native Americans called the lake E-e-kwahl-a-mat-yam-lshkt, "heart of the mountains". The name Lost Lake came from Mack Hollamon, a hunting and fishing guide around the turn of the 19th century who had worked throughout Mount Hood for years without finding the lake until Native Americans showed him where it was. The area is part of the proposed Lewis and Clark Mount Hood Wilderness.

Native Americans called the lake E-e-kwahl-a-mat-yam-lshkt, "heart of the mountains". The name Lost Lake comes from Mack Hollamon, a hunting and fishing guide around 1900 who travelled Mount Hood for years without finding the lake until Native Americans showed him where it was. Motor craft are not allowed, so canoes, row boats and kayaks set the pace on the water.

The resort sits at the lake's north end, where the outlet forms the source of Lake Branch Hood River. It holds 125 primitive campsites, seven rustic cabins and a rustic general store, open May through October. Canoes, rowboats and kayaks can be rented; motor craft are not allowed. A day-use fee is charged per vehicle at entry, paid to the concessionaire.

Under specific weather conditions in early fall, a perfect reflection of Mount Hood forms on the water surface, drawing photographers from throughout the Pacific Northwest region. This phenomenon occurs most frequently during early morning hours when wind and wave action are minimal.