Henry's Lake is a natural glacial-filled lake which, along with its tributaries, is the headwaters for the Henry's Fork of the Snake River. The lake is famous for its trout fishing, and the flat is considered one of the most ecologically significant regions in the Greater Yellowstone Ecosystem.
The area's wide open grasslands and wetlands are critical habitat for peregrine falcons, gray wolves, bald eagles and grizzly bears, and crucial habitat for large numbers of big game, waterfowl and sandhill cranes.
The lake and flats are renowned for their vast, diverse and unique wetlands and miles of spring creeks. This is the only place in Idaho with white spruce — the rare Picea glauca. Hoary willow, mountain willow, swamp willow weed, green keeled cottongrass and pale sedge — all of which are rated rare in Idaho — also grow in the area.
The white spruce grow on peat soils believed to be remnants of floating islands recorded by early trappers who worked the area. These unique features led early explorers to believe that Henry's Lake should be part of Yellowstone National Park.
The Henry's Lake Wilderness Study Area (WSA) lies within the ACEC boundaries.
On the southeastern shore of the lake is Henrys Lake State Park with a boat ramp and modern fish cleaning station.
The lake is also accessible (without developed facilities) from BLM-administered lands.