Wild Horse Island State Park

Wild Horse Island is the largest island in Flathead Lake, about 2,160 acres of grassland, ponderosa pine and rocky knolls, and a day-use state park that you can reach only by boat. It lies off Big Arm Bay on the west side of the lake, within both Lake County and the Flathead Indian Reservation. The island is known for its wildlife: bighorn sheep, mule deer, bald eagles, falcons, waterfowl and songbirds, plus a small band of wild horses. Montana Fish, Wildlife & Parks says five horses live there.

The Salish and Kootenai people used the island to pasture horses, where they were safe from raids by other tribes, which is the origin of its name. It was part of the reservation from 1872 until 1904, when the land was divided into individual plots. Homesteaders cut much of the old timber between about 1910 and 1915 and tried farming without success. The state began protecting it as a park in 1977; around 56 private lots remain on the island, so respect posted private land. Bighorn sheep were introduced in 1939, and the herd has since been large enough to supply sheep to other herds in northwest Montana.

The island rises from the shoreline at about 2,900 feet to a high point about 850 feet above the lake, shaped by the glacier that once filled the valley. Trails run from the landing sites through pine forest and over open grassland to viewpoints over the lake; FWP publishes a trail map. Meadows on the west and south sides are among the last remnants of native shortgrass prairie in the area.

There is no public dock and no ferry run by the park, and you must use one of the six designated landing sites, not the private docks. Camping is not allowed, and pets are banned to protect the wildlife. Bears visit the island and there are no food lockers, so keep food on your boat or with you. Approaching within 100 feet of any animal, including the horses, or feeding them is a violation. Groups over 15 need a special use permit. The island is open all year for day use, and FWP listed no 2026 closures.

Practical tip: the lake can turn rough quickly on summer afternoons. Check the National Weather Service forecast for Flathead Lake before crossing, plan your landing for the morning, and pack out everything you bring.