Fly fishing enthusiasts and river lovers will find easy access to Henry's Fork at this Forest Service campground positioned along Highway 20. Flat Rock accommodates RVs up to 65 feet with electric hookups available at select sites, though the access road can present challenges during wet conditions. The 20 sites spread across forested and open terrain, with some positioned closer to the water for direct river access.
Camp hosts maintain the facilities daily and provide firewood for purchase, as natural sources prove scarce in the area. Bear boxes appear every few sites, and clean restrooms serve the campground, though no shower facilities exist. "Easy access to the river" draws anglers targeting trout, while the proximity to Highway 20 means some traffic noise carries through the sites. Despite the road sounds, many campers extend their stays to take advantage of the fishing opportunities and the campground's location just 35 minutes from Yellowstone's entrance.
Sites with electric hookups run $25-26 per night, while standard sites cost less. The campground operates from mid-May through mid-September, with temperatures dropping significantly at night even during summer months. Brianna W. notes the facility is "very clean with bathrooms close by," making it suitable for both RV travelers and tent campers seeking a base for Yellowstone exploration or Henry's Fork fishing adventures.
Description
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.
RV Road Trip Guides
Map & DirectionsFlat Rock (idaho) is located in Idaho near Macks Inn
Directions
From West Yellowstone, Montana, take U.S. Highway 20 south for 22 miles, or from Ashton, Idaho, take U.S. Highway 20 north for 30 miles. The campground entrance is 1/4 mile south of Macks Inn on the west side of the highway.
Address
HIGHWAY 20
Island park, ID 83429
Coordinates
44.4969444 N
111.34 W
Connectivity
T-Mobile is introducing T-Satellite to extend coverage in the outdoors
T-Mobile5GExcellent CoverageVerified by 31 usersLast on 5/10/26- Verizon5GExcellent CoverageVerified by 17 usersLast on 5/10/26
AT&TLTEGood CoverageVerified by 11 usersLast on 5/10/26
Connectivity
T-Mobile is introducing T-Satellite to extend coverage in the outdoors- T-Mobile5GExcellent CoverageVerified by 31 usersLast on 5/10/26
- Verizon5GExcellent CoverageVerified by 17 usersLast on 5/10/26
- AT&TLTEGood CoverageVerified by 11 usersLast on 5/10/26
Access
- Drive-InPark next to your site
- Walk-InPark in a lot, walk to your site.
- Hike-InBackcountry sites.
- Boat-InSites accessible by watercraft.
Site Types
- Tent Sites
- RV Sites
- Standard (Tent/RV)
- Group
- Cabins
- Tent Cabin
Features
For Campers
- Market
- Trash
- Picnic Table
- Firewood Available
- Phone Service
- Reservable
- WiFi
- Drinking Water
- Electric Hookups
- Toilets
- Alcohol
- Fires
For Vehicles
- Sanitary Dump
- 50 Amp Hookups
- Big Rig Friendly
Drive Time
- 1 hr 15 min from Idaho Falls, ID
- 1 hr 58 min from Bozeman, MT
- 1 hr 59 min from Pocatello, ID
- 2 hrs 40 min from Helena, MT
