A gravel road curving into a high mountain valley at first light, the peaks catching the sun.

Forest Service campground

Flat Rock

Forest Service campground in Caribou-Targhee National Forest, Fremont County, Idaho. About 6,400 feet. 2.6 miles from Island Park.

Managed by
Forest Service Caribou-Targhee National Forest
Elevation
About 6,400 ft As the Forest Service states
Sites
16 10 standard non-electric, 6 standard electric
Longest rig
65 ft The longest vehicle any site is listed for
Hookups
Electric
Reservations
Recreation.gov

Overview

Flat Rock Campground is located 22 miles south of West Yellowstone, Montana and 30 miles north of Ashton, Idaho in beautiful Island Park, Idaho. Flat Rock is adjacent to U.S. Highway 20 and the Henry's Fork of the Snake River at an elevation of 6,400 feet.

Recreation

Henry's Fork has great fly-fishing for rainbow and brook trout. The river's headwaters are at Big Springs, one of the nation's largest springs, just 4.5 miles from the campground. Tubing, canoeing, kayaking and rafting are also popular on the river.

The Big Springs National Recreation Water Trail begins at Big Springs and ends just northeast of the campground at Macks Inn. It offers a lazy three-hour float or canoe trip through beautiful scenery. Wildlife, including moose, bald eagles and Sandhill cranes, is often seen along the trail.

Hiking, biking, horseback riding and ATVing are popular activities. Many miles of trails crisscross Island Park, including the 2.5-mile Coffee Pot Rapids Trail, which begins at nearby Upper Coffee Pot Campground and meanders along the riverbank. The Continental Divide National Scenic Trail and the Nez Perce Trail are in the area.

Island Park Reservoir and Henry's Lake are nearby, both offer boating, water skiing and excellent fishing opportunities.

Facilities

The campground contains single and double campsites, some of which have 50-amp electric hookups. Sites are equipped with picnic and utility tables, a campfire ring and tent pad.

Vault toilets, drinking water and trash collection are provided. All interior roads and parking spurs are gravel.

Macks Inn is just across the highway from the campground and offers amenities such as boat rentals, shuttle service, showers, laundry facilities, gas and groceries.

Natural Features

Island Park is composed of two areas of extinct volcanic activity. The Henry's Fork Caldera sits inside the larger Island Park Caldera. The area is known for its dense forests of lodgepole pine, broad grassy meadows bursting with summer wildflowers and a wide variety of wildlife, including black and grizzly bears, moose, elk, deer, bald eagles, Sandhill cranes and much, much more.

A mixed growth of lodgepole pine forest provides partial shade. A portion of one loop is fairly close to the river and some sites have river views.

Nearby Attractions

Mesa Falls Scenic Byway is 11 miles south of the campground. This 28-mile road leads to scenic overlooks and trails at 110 foot Upper Mesa Falls and 85 foot Lower Mesa Falls.

Harriman State Park is 13 miles south. The Henry's Fork meanders through the Harriman, offering excellent fishing. Over 20 miles of trails are available, and wildlife is abundant in this scenic park.

Henry's Lake State Park is 10 miles north, offering fishing, a fish cleaning station and boat ramp.

Yellowstone National Park's west entrance is just 22 miles north in the town of West Yellowstone, Montana. Visitors enjoy day-tripping to the park for unparalleled wildlife viewing and the beautiful and unique scenery.

The description, directions and fees are the Forest Service’s own words, from its record on Recreation.gov.

What people do here

  • biking
  • boating
  • camping
  • fishing
  • hiking
  • hunting
  • wildlife viewing

The land around Flat Rock

The ringed pin is this campground; the others are its nearest neighbours. Switch on forest roads or BLM routes to see the way in.

Interactive map. Drag to pan, scroll or pinch to zoom, and select any point to see which agency manages the land. Arrow keys pan and the plus and minus keys zoom when the map has focus. A list of every state with its share of federal land is on the Explore page.

Map layers

Layers
Base map
Legend

Federal land, by managing agency

  • Bureau of Land Management (BLM)
  • US Forest Service (USFS)
  • National Park Service (NPS)
  • US Fish and Wildlife (USFW)
  • Bureau of Reclamation (USBR)
  • Department Of Defense (DOD)
  • Bureau of Indian Affairs (BIA)
  • Other Federal
  • State
  • Local
  • Alaska Native Lands (Patented or Interim Conveyed)
  • Alaska Native Allotment

Federal campgrounds, by agency

  • Forest Service
  • Bureau of Land Management
  • National Park Service
  • Army Corps of Engineers
  • Reclamation, Fish and Wildlife and others

State and local land (USGS PAD-US)

  • State land
  • County and city land
  • Regional agency or district
  • Land trust or conservancy

Gaps with no tint inside public land are private parcels, often old mining claims and homesteads. They are not open to the public.

Dashed clay lines on the base map are unpaved tracks from OpenStreetMap. They show what exists on the ground, not what is legal to drive.

Select any point to see who manages the land.

Boundaries are approximate and land status changes. This map is a planning aid, not a survey or a statement of access. Confirm routes, closures and camping rules with the managing office.

Source: Recreation Information Database (Recreation.gov), record updated February 25, 2026. Elevation from the USGS 3D Elevation Program. Seasons, fees, water and fire rules change; the managing office has the final word.