Grand Teton National Park

Just off of the main road through the Grand Teton National Park, a bit North of Moose Junction (in the South of the park), there's a little rest area from which a small trail leads towards the swampy shores of the Snake river. Look for the signs to Schwabacher's Landing. The trail is only a fairly short hike, absolutely flat (thus not exactly challenging), but offering beautiful views on the Grand Teton peaks mirroring in the water of the swamps. And if you're lucky, you may actually spot a beaver there as well...