Lost Lake is a secluded 163-acre lake located in Minnehaha County, South Dakota, approximately 2.5 miles north of Humboldt along Highway 19. This quiet waterbody offers paddlers a peaceful retreat characterized by its irregular shoreline with several large peninsulas and scattered woodland along the shore. The lake's remote setting, hidden by surrounding hills, earned it the "Lost Lake" name and continues to provide a sense of seclusion with very few buildings within sight and minimal visitor activity.

Access to Lost Lake requires navigating rough, unmarked dirt roads that can be challenging, especially after rain for two-wheel drive vehicles. The primary access point is reached by traveling east on 256th Street from Highway 19, then north on 458th Avenue, and west along a dirt track road through the woods leading to the launch area. GPS navigation is recommended as signage is limited. The entrance passes through a wildlife production area, and the South Dakota Game, Fish and Parks manages the site.

The lake spans approximately 163 acres with about 3 miles of shoreline and has an average depth around 10 feet, with maximum depths reaching 40 feet. Water clarity can vary, with the lake sometimes displaying a greenish algae tint. Paddlers should be cautious of dead tree remnants protruding from the water near the southern portion of the lake, evidence of rising water levels over the years that drowned a stand of trees. The shallow depth in some areas requires attention to underwater debris and vegetation.

Wildlife viewing opportunities include lone pelicans, gulls, ducks, geese, egrets, and blue herons. The relatively undeveloped shoreline features tall grasses, a few scattered trees, and dense cattail populations in some areas.

Fishing is popular here, with the lake stocked with northern pike, walleye, yellow perch, crappie, and black bullhead. A $6 day-use vehicle fee applies. No facilities or services are available at the access point, so paddlers should bring adequate water and supplies.