We took many trips to Wildhorse Island State Park while we were camp hosting at Big Arm, Flathead Lake. The island is a state park accessible only by boat. You can get there from Polson, Lakeside or Big Fork.
Wildhorse Island boasts tons of big horn sheep which are very people-friendly. There are also 5 wild horses (yes, only 5) on the island, but in all our trips there we never saw even one :(
The island has had some of the largest big horn sheep found in North America, and they are quite spectacular creatures, especially seeing them up close and personal.
There are a couple of loops around the island that take you through corrals, orchards, grassy hills, forests, a homestead, and of course some beaches.
There are also 50 private homes that were grand-fathered in as private property when the island became a state park.
This island is definitely worth a trip out to if you are in the area!