Flatrock Campground

Flat Rock Campground is nestled along the banks of the Henrys Fork of the Snake River, about 22 miles south of West Yellowstone, Montana, in scenic Island Park, Idaho. Situated within the Caribou-Targhee National Forest’s Ashton/Island Park Ranger District, this campground rests at an elevation of 6,400 feet, accessible via U.S. Highway 20, just across from Mack’s Inn Resort.

Natural Features: A mixed forest of lodgepole pine sweeps across the campground, offering partial shade to its sprawling sites, while the Henrys Fork meanders past the lower loop, its waters alive with rainbow, brook, and cutthroat trout. Summer wildflowers dot the grassy edges, framing this tranquil retreat against the volcanic caldera of Island Park.

The river beckons with world-class fly-fishing, tubing, canoeing, and kayaking, with the Big Springs National Recreation Water Trail—a lazy three-hour float—starting 4.5 miles upstream at one of the nation’s largest springs. The Mesa Falls Scenic Byway, 11 miles south, unveils stunning overlooks at Upper and Lower Mesa Falls, while trails for hiking, biking, and ATVs crisscross the surrounding forest.

Facilities: The campground offers 37 single-family sites and one double-family site, each equipped with picnic tables, campfire rings, and tent pads; six sites boast 50-amp electric hookups. Vault toilets, drinking water, and trash collection are available, with a campground host on-site to assist. Roads and parking spurs are gravel, accommodating RVs up to 65 feet.

Season: Late May-Early September

After season: Open (weather dependent) first-come/first-served; no fee, no toilets, no water.