We wouldn't exactly make the claim that the snowmobiling in Wyoming's Sublette County is an island unto itself, but if you were stranded . it wouldn't be a bad place to be stuck snowmobiling.
We say it's not an island unto itself because the trail systems that enter and exit the county on the east, north and west sides all lead to great riding, but if you never left the county, then you'd be in for some spectacular riding as well.
Spectacular because the county is nearly surrounded by mountains. The Wind River Mountains form much of Sublette County's eastern border while the Wyoming Range flanks the western border. On the north side of the county sits the southern part of the Gros Ventre Range. Those are three of Wyoming's most famous and spectacular mountain ranges. High desert makes up the southern portion of the county.
While it would be nice to say that snowmobiling is wide open all across the 4,886-square mile county, that's not the case. Much of the Wind River Mountains are in the Bridger Wilderness and off limits to snowmobiling. Part of the Gros Ventre Wilderness fills the northcentral portion of the county and there are several winter ranges set aside for wildlife scattered across the county. There are a handful of trails that go through the winter ranges but sledders are restricted to the trails through those areas, which are clearly marked on the snowmobile trail map. On one of our rides through a winter wildlife range while sledding on the Continental Divide Snowmobile Trail we were able to watch a large herd of elk being fed from a horse-drawn sleigh.