Pristine and wild natural park in Idaho
The curiously-named Frank Church River of No Return Wilderness is one of the largest and most amazing wilderness areas in the continental United States. When I say it's large, I mean it's MASSIVE. It covers over 2.3 million acres of mountains, meadows, rivers, hot springs, and forests in central Idaho and one of the last remaining areas to see moose, bear, wolves, elk, and other spectacular large North American mammals in their natural habitat.
The Frank Church River of No Return Wilderness is probably most famous for rafting. In fact, the park gets its strange name from the Salmon Falls river's strong current which made it tough for boats to make it back up stream in the past. These days, you'll find plenty of outfitters in the area that'll take you on single of multi-day rafting adventures down the river.