The Snake River used to flow across the northern portion of the Snake River Plain, but now flows along the southern margin of the Plain. The river was pushed there by successive lava flows. Sixty six thousand acres are within a Wilderness Study Area (WSA). The northwest end of the lava flow has been designated as a National Natural Landmark by the US Park Service. Today, three trails go across this desolate landscape, one primitive and the other two developed with interpretive signs. Even though this area looks uninhabited, it is growing and alive with wildlife and vegetation.
About 20 miles southwest of Idaho Falls and 5 miles east of Blackfoot. From I-15, take the "Blackfoot Rest Area" exit. Access the trails from the parking areas.
http://www.tripleblaze.com/trail.php?c=3&i=8396