Twenty Mile Trail

Lava Trail System (Hell'S Half Acre), Near Idaho Falls, Idaho

Twenty Mile Trail does not offer reservations through Please take a look at the area details below for more information about visiting this location. Enjoy your visit!


These undeveloped trails offer scenic solitude; there is a short 0.5 mile loop trail and a 4.5 mile trail to the main vent of the Hell's Half Acre flow. Trail routes are marked with poles across lava. A picnic area, fire ring and portable toilets are located at the trail-head. This is treacherous rocky terrain and proper footwear is advised. It also gets very hot and there is little to no shade so proper sun protection and water is advised.