Henrys Lake is a small, shallow natural alpine lake

Alpine lake

Alpine lakes are classified as lakes or reservoirs at high altitudes, usually starting around 5,000 feet in elevation above sea level or above the tree line....

, approximately 8 square miles (20.7 km²) in area, at 4 miles (6.4 km) in length and 2 miles (3.2 km) in width. It is located at 6472 feet (1973 m) above sea level in the mountains of southeastern Idaho

Idaho

Idaho is a state in the Rocky Mountain area of the United States. The state's largest city and capital is Boise. Residents are called "Idahoans". Idaho was admitted to the Union on July 3, 1890, as the 43rd state....

 in the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

. It is on the southwest side of the Henrys Lake Mountains

Henrys Lake Mountains

The Henrys Lake Mountains, el. , is a small mountain range northwest of West Yellowstone, Montana in Madison County, Montana....

 of northern Fremont County

Fremont County, Idaho

Fremont County is a county located in the U.S. state of Idaho. The county was established in 1893, and was named for the explorer John C. Frémont. As of the 2000 census the county had a population of 11,819 . The county seat and largest city is St. Anthony...

, approximately 2 miles (3.2 km) south the continental divide along the Montana

Montana

Montana is a state in the Western United States. The western third of Montana contains numerous mountain ranges. Smaller, "island ranges" are found in the central third of the state, for a total of 77 named ranges of the Rocky Mountains. This geographical fact is reflected in the state's name,...

 state line, just west of Targhee Pass

Targhee Pass

Targhee Pass is a mountain pass located on the Continental Divide in the Henrys Lake Mountains, along the border between southeastern Idaho and southwestern Montana, at an elevation of 7072 feet above sea level....

. The lake is located in Caribou-Targhee National Forest

Caribou-Targhee National Forest

Caribou-Targhee National Forest is located in the states of Idaho and Wyoming, with a small section in Utah in the United States. The forest is broken into several separate sections and extends over . To the east the forest borders Yellowstone National Park, Grand Teton National Park and...

.

The lake provides the headwaters of the Henrys Fork, a tributary of the Snake River

Snake River

The Snake is a major river of the greater Pacific Northwest in the United States. At long, it is the largest tributary of the Columbia River, the largest North American river that empties into the Pacific Ocean...

. The lakes lies less than 10 miles (16 km) across the continental divide from the headwaters of the Missouri River

Missouri River

The Missouri River flows through the central United States, and is a tributary of the Mississippi River. It is the longest river in North America and drains the third largest area, though only the thirteenth largest by discharge. The Missouri's watershed encompasses most of the American Great...

in southwestern Montana.

Henrys Lake State Park is on the shore of the lake.