Twentymile Lava Trail is a 9.6 mile moderately trafficked out and back trail located near Idaho Falls, Idaho that features beautiful wild flowers and is rated as moderate. The trail is primarily used for hiking, walking, and trail running and is best used from March until October. Dogs are also able to use this trail.
A 0.9-mile loop or a 4.5-mile trail to the main vent of the flow. Both are unimproved and marked with poles. Hiking in lava fields is unique because of the rough terrain, unusual scenery, and the contorted landscape. Since this is a Wilderness Study Area (WSA), permanent trails have not been developed. The unimproved hiking routes are marked with poles. Blue top poles mark a route around a short loop which is a good introduction to lava hiking. The 0.9-mile loop takes about 30 minutes to walk. On this loop note the pressure ridges, deep cracks with ferns at the bottom, and moss on rocks. Red top poles mark a 4.5-mile route to the main vent or source of Hell's Half Acre lava flow. This is a strenuous hike and a round-trip to the vent can take a full day. Water is essential and boots with good soles are advisable. Estimated time to hike to the vent is 2-3.5 hours (one way).
Be careful of temperature on the trail. Start early. It gets hot! Take lots of water. It is a little difficult to see some trail markers.
Really pretty. A more difficult hike because you're scaling lava fields. Not good for dogs, cactus everywhere and a little rough on the pads.
It is a very hot hike on the lava rocks. There was a lot of cactus flowers and a few rabbits. There is not a trail that is visible for the majority of the hike and you must find the trail posts to follow. The hike was 10 miles to get to the end of the markers. I would recommend starting the trail early and plan on around 4+ hours.
Amazing weather! Lost the blue poles 3/4 of the way around the loop but found our way back. Definitely will be back for the longer out and back.
A real good spring or fall hike. Stay away once the temperature gets into the 70's. Bring water and wear above the ankle boots. The spring colors will surprise you.
One of my favorite spring hikes! Beautiful desert landscape! Enjoy the spring foliage including lichen, juniper bushes, sage brush, sego lily and prickly pear cactus. This is rattlesnake territory, but the rattlesnakes stand out against lava rock and I have only seen them on warm days. I start hiking here as soon as the snow has melted off the ground in town.
Once the temperatures get above 75 degrees I avoid this one. The lava rock gets hot! The trailhead can be difficult to find, the sign does not reference to the 20 mile, but says soemthing like "Lava trail." The trailhead is almost exactly 20 miles west on Hwy 20 from the intersection of Bellin Road and Hwy 20. There is a picnic area, but no restroom or outhouse or water. The trail follows tall poles. The blue poles take you in a short loop--at the far end of the loop, you can continue on the out and back with the red poles. The poles can be a little bit difficult to see, so avoid trekking back at sunset if you are unfamiliar with the area. However, the sunset is beautiful here with views of some of the buttes in the west and southwest and the Pioneer mountains. Wear sturdy shoes and watch your foot placement--there are plenty of cracks, loose rocks and lots of uneven ground. The vent is pretty cool, but I think this is one hike that the journey is at least as good as the destination.
Rough tough hike make sure you bring plenty of water.