Horse Thief Lake is a lake

Lake

A lake is a body of relatively still fresh or salt water of considerable size, localized in a basin, that is surrounded by land. Lakes are inland and not part of the ocean and therefore are distinct from lagoons, and are larger and deeper than ponds. Lakes can be contrasted with rivers or streams,...

 in Pennington County

Pennington County, South Dakota

As of the census of 2000, there were 88,565 people, 34,641 households, and 23,278 families residing in the county. The population density was 32 people per square mile . There were 37,249 housing units at an average density of 13 per square mile...

, South Dakota

South Dakota

South Dakota is a state located in the Midwestern region of the United States. It is named after the Lakota and Dakota Sioux American Indian tribes. Once a part of Dakota Territory, South Dakota became a state on November 2, 1889. The state has an area of and an estimated population of just over...

. It is approximately two miles to the northwest of Mount Rushmore

Mount Rushmore

Mount Rushmore National Memorial is a sculpture carved into the granite face of Mount Rushmore near Keystone, South Dakota, in the United States...

, making it the closest lake to that monument. It appears to be the lake seen north of Mount Rushmore in the 2007 Disney movie National Treasure 2: Book of Secrets when the entrance to the secret golden city of Cibola

Quivira and Cíbola

Quivira is a place first mentioned by Francisco Vazquez de Coronado in 1541, who visited it during his searches for the mythical "Seven Cities of Gold". The location and identity of the "Quivirans" has been much debated over a wide area, including Kansas, Nebraska, and Missouri...

 is found. However, the lake actually used in the film is the nearby Sylvan Lake, five miles southwest of the monument.