Henrys Lake is a small, shallow natural alpine lake, 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 in the United States. It is on the southwest side of the Henrys Lake Mountains of northern Fremont County, approximately 2 miles (3.2 km) south the continental divide along the Montana state line, just west of Targhee Pass. The lake is located in Caribou-Targhee National Forest.
The lake provides the headwaters of the Henrys Fork, a tributary of the Snake River. The lakes lies less than 10 miles (16 km) across the continental divide from the headwaters of the Missouri River in southwestern Montana.
Henrys Lake State Park is on the shore of the lake.