There Is One Place in Montana Where Bighorn Sheep Walk Down to the Water While You Cast a Fly Rod

Wild Horse Island sits about two miles off the western shore of Flathead Lake — the largest natural freshwater lake in the western United States — and it belongs to a very short list of places that genuinely exceed the imagination. A 2,160-acre Montana state park accessible only by boat, the island has no roads, no restaurants, no crowds. What it does have is a herd of bighorn sheep that have never been hunted, wild horses that trace their lineage to the Salish-Kootenai tribes who pastured horses here centuries ago to keep them safe from rival tribes, and some of the clearest, coldest, most productive fishing water in the northern Rockies.

Riverstone Outfitters runs the only guided boat tour to Wild Horse Island currently marketed by a licensed Montana outfitter. That distinction matters. It means your guide knows the water, knows where the fish hold, and knows exactly where on the island to anchor so you can watch bighorns move through old-growth ponderosa pine above the shoreline — all in the same half day.

What to Expect on the Water

Your day begins at our departure point in Dayton or Polson, Montana, at the western shore of Flathead Lake. From there, your guide pilots a private boat — comfortable, covered, and outfitted for up to six guests — across open water with the Mission Mountains rising to the east and the Swan Range framing the horizon.

The crossing itself is part of the experience. Ospreys work the surface near the narrows. Bald eagles post up on the rocky points that ring the island. On calm summer mornings, the lake surface holds reflections of everything above it.

Once you arrive at the island, the tour is shaped around what the day offers. Wildlife is unpredictable in the best possible way. Your guide reads the water, the light, and the wind, then decides where to anchor, when to drift, and when to cut the engine entirely so you can watch without disturbing anything. The fishing and the wildlife viewing weave together naturally — there is no schedule that forces one or the other.

The season runs May through October. Spring brings wildflowers and active fish post-ice-out. Summer offers long days and warm water. Fall is arguably the finest time: the bighorns are at their most visible, the lake trout are feeding hard before winter, and the crowds on the mainland are gone.

Wildlife You'll See

Wild Horse Island earned its reputation as one of the premier wildlife-viewing destinations in Montana. In 2016, a ram found on the island was assessed by the Boone and Crockett Club as the new world-record bighorn sheep — the largest horns ever recorded for the species, beating the previous record by nearly seven inches.

• Bighorn sheep — the island's herd numbers in the dozens; rams with full curls are a common sight on the rocky bluffs above the landing beaches
• Bald eagles — nesting pairs are present throughout the season; your guide carries binoculars for close views
• Mule deer — often visible near the tree line in the morning hours
• Osprey — hunting the same shallows where you'll be casting
• Wild horses — five mares, descendants of horses the Salish-Kootenai pastured here, tend to graze near the southern tip of the island

Fly Fishing Flathead Lake

Flathead Lake is one of Montana's most underrated fisheries. Riverstone's guides know where the trophy species hold.

Lake Trout (Mackinaw) — The primary target on the lake tour. These fish run large, fight hard, and require techniques your guide will walk you through completely.

Bull Trout — A federally threatened species managed under strict regulations. Your guide will brief you on current rules. Catching and observing a bull trout in the wild is something most anglers remember for a long time.

Westslope Cutthroat Trout — The native trout of this drainage. Shallower structure near the island holds cutthroat responsive to streamers and, on the right evening, surface presentations.

All gear is provided — rods, reels, flies, and terminal tackle. A Montana fishing license is required and not included; a 1-day non-resident license runs approximately $15 and can be purchased online before arrival.

The Combo Trip

For guests who want to go deep on both the fishing and the wildlife, Riverstone offers a combined Flathead Lake Charter + Wild Horse Island Tour. The morning is spent fishing the most productive structure on the lake. The afternoon shifts to an anchored tour of the island shoreline and a guided walk ashore. It is a full day and a complete experience of what makes this corner of Montana worth the drive.

Who This Trip Is For

The honest answer is: almost anyone. This is not a trip that requires fly fishing experience, athletic ability, or any special knowledge of Montana. The boat holds six guests maximum. Families with children have taken this trip and come back the following year. Non-anglers who simply want to be on the water near the island are just as welcome as the angler who has been planning a Flathead Lake trip for a decade.

Kids, seniors, and guests with limited mobility are all accommodated. The boat is stable and comfortable. Life jackets are provided and required.

Book Your Wild Horse Island Boat Tour

Riverstone Outfitters guides this trip seasonally from May through October. Departures are from Dayton or Polson on Flathead Lake. Private trips for up to six guests are available. Dates fill quickly in July and August — book early.

Book the Wild Horse Island Boat Tour →

Frequently Asked Questions

What wildlife can I see on Wild Horse Island?
Wild Horse Island is home to bighorn sheep, mule deer, bald eagles, osprey, and a small herd of wild horses descended from horses the Salish-Kootenai tribes pastured here centuries ago. In 2016, a ram from the island was certified by the Boone and Crockett Club as the new world-record bighorn sheep. Wildlife is visible from the water and shoreline throughout May through October.

Do I need fishing experience for the Wild Horse Island tour?
No experience is necessary. Guides teach casting on the water. All equipment is provided — rods, reels, flies, and tackle. A Montana fishing license (~$15/day for non-residents) is the only requirement to arrange in advance.

Can kids go on the Wild Horse Island boat tour?
Yes. The trip is designed for all ages. The private boat holds up to six guests and is stable and comfortable. Life jackets are provided and required. Families are welcome.

What is included in the Wild Horse Island tour?
The tour includes the private boat, licensed guide, life jackets, fishing rods and tackle, binoculars, and guided narration. Not included: food and beverages, gratuity, and a Montana fishing license (~$15/day).

How do I get to Wild Horse Island, Montana?
Wild Horse Island is accessible only by boat — no roads or bridges connect it to the mainland. Riverstone Outfitters departs from Dayton or Polson, approximately 65 miles south of Whitefish and 75 miles south of Glacier National Park.