Roberts, Idaho · Bonneville County · Facility
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 prop…
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.
From Idaho Falls, travel west on Highway 20 to mile marker 287. Continue 0.3 miles until you see a sign for "Lava Trail." Turn left onto the gravel road (staying left at the fork) and continue one-quarter mile to the trailhead.
Driving directions (Google Maps) →Heading to Twenty Mile Trail? A few things to know before you go:
Photo: Tobias MrzykIdaho's longest mapped hiking trails, ranked by distance with notes on what makes each route worth the commitment.
Photo: Sergei AkulichSteep is hard. These are the ten Idaho trails with the most total elevation gain — quad-burners earned by hard climbing.
Photo: Joshua EarleTen gentle, well-marked Idaho trails perfect for first-time hikers, families, or recovery days.
Photo: Sergei AkulichIdaho's ten hardest hikes — expert difficulty, big mileage, or serious exposure. Reserved for experienced hikers.
Photo: Joshua EarleFederal parks and recreation areas in Idaho ranked by what they actually offer hikers and campers, not just popularity.
Photo: Joshua EarleIdaho's best hikes to named waterfalls — from short family-friendly viewpoints to all-day cascade chasing.