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.
Twenty Mile Trail is primarily first-come, first-served. Use the availability view to gauge how busy it is before you go.
See the map for Twenty Mile Trail's exact location and directions.
Pick your dates on the availability calendar, then reserve through the official booking link. You can also set an alert and we'll notify you if a sold-out date opens up.