Big Springs is a free, easy stop in Island Park where the Henrys Fork of the Snake River starts. It pours out more than 120 million gallons of water a day at about 52°F, and you can watch huge trout from a footbridge.1,4
What Big Springs is
Big Springs is the headwaters of the Henrys Fork and one of the largest springs in the country.3 The water comes out of the ground at about 52 degrees year-round. It's clear enough to see the plants on the bottom.4
It was named a National Natural Landmark in 1980.1 The river starts right here.
What you'll see
Start at the footbridge. Big rainbow and brook trout hang out right under it, and the kids can get a good look at them.4
From there, the half-mile accessible trail follows the water. Keep an eye out for osprey, bald eagles and waterfowl, and once in a while a moose or a muskrat.4
Before you head over
- You can't fish from Big Springs down to where the Henrys Lake Outlet joins the river. Check Idaho Fish and Game's rules before you fish farther down.5
- This is bear country. Keep food in the car or a bear-proof container.
- Once the snow piles up, getting to the springs can be harder.4
- Restrooms and the campground are seasonal, roughly late May to early September.3
The Johnny Sack Cabin
Look across the water and you'll see Johnny Sack's cabin. He leased the land from the Forest Service in 1929 and built the cabin mostly by hand in the 1930s.2,6 It's on the National Register of Historic Places, and you can usually tour it mid-June through mid-September. The Forest Service, Fremont County and local volunteers keep it open.2
Owner's tip
Make it one trip. Big Springs and the boat launch are in the same area, so load the kayaks and paddleboards from the garage before you leave (or rent tubes in town), check out the springs and the bridge first, then drive about a mile west to the boat launch. That's as close to the springs as you can put in. It's a slow, easy float, so plan on a good three hours to Mack's Inn. No matter how many are in your group, have a plan to get back. Ideally bring two vehicles, park one at Mack's Inn and one at the boat launch, so you have a car at both ends. (Hitchhiking back doesn't count as a plan.)
The float to Mack's Inn
The float starts at the Big Springs boat launch, about a mile west of the springs, and runs about 4.5 miles down to Mack's Inn.3 The water moves slow the whole way. We've got some life jackets at the cabin too.
No kayaks of your own? Mack's Inn rents tubes, kayaks, canoes, rafts and paddleboards from Memorial Day to Labor Day. Paddles, life jackets and a ride up to the launch come with it. You can also pick up tubes at a few of the stores around Island Park.
When to go
Come in summer if you want to see inside Johnny Sack's cabin. It's usually open mid-June through mid-September.2 If you're coming early or late in the season, check that the campground and boat launch are open before you head over.3 Fall is usually quieter.
Quick answers
Is Big Springs free?
Yes. There's no fee to visit the springs, the bridge or the trail.
Can you fish at Big Springs?
No. You can't fish from Big Springs down to where the Henrys Lake Outlet joins the river. Check Idaho Fish and Game's rules before you fish farther down.5
How long should we plan?
Plan on about an hour for the bridge and trail. Give yourself a little longer if the cabin is open and you want to look inside. Add about three hours, plus the car shuttle, if you float to Mack's Inn.
- Big Springs (Idaho), Wikipedia: flow, National Natural Landmark (1980)
- Johnny Sack's Cabin, Yellowstone Teton Territory: history, season, National Register
- Big Springs Campground, USDA Forest Service: distance, season, water trail
- Big Springs, Visit Idaho: temperature, trail, wildlife, fishing, winter access
- Idaho Fish and Game Fishing Planner: fishing closure below Big Springs
- National Register nomination, Johnny Sack Cabin (NPS): 1930s construction
