This trail is listed as "doubletrack." The northern portion of this trail is definitely a dirt road and is used by the park service to take tour groups to Fern Cave. The southern portion of this trail is a mix of both singletrack and unused dirt road.
This trail is point-to-point. Therefore, if you have access to multiple vehicles, you can leave a vehicle at one of the two trailheads and use it to return to your other vehicle after you finish. Parking space is plentiful at or very near the two trailheads. You can also double back along the trail to where you started. However, be sure to carry plenty water as there is none in the park and this option would require a 20-mile round-trip journey on an exposed trail. It is also possible to camp in the backcountry at Lava Beds, NM and this trail is an excellent option for doing so.
The southern trailhead is located at the end of Skull Cave Road and near the entrance to Skull Cave. From here, follow the trail by walking around a rock barrier that blocks vehicle access to the trail and pass a small bathroom. Initially, the trail follows near the Modoc Lava Tube System, a lava tube system that originates at Modoc Crater and stretches for 10 miles to the old shoreline of Tule Lake. Many collapsed tubes and skylights are visible along this portion of the trail.
After about 1.5 miles, the trail passes the Three Sisters Trail
moving east. The Three Sisters are three cinder cones to the east of Lyons Trail.
Continuing north, the trail passes through rough lava flows and eventually reaches Juniper Butte. Juniper Butte is dotted with junipers and is the only place along the trail that provides shade. On the north side of Juniper Butte is a dirt road similar looking to Lyons Trail but heading east. Do not take this road. It leads out of the monument to Highway 120 after some miles.
A little further north, the trail passes a couple of trails that lead to Fern Cave. The first trail is a singletrack to the east. Just beyond that is a short dirt road also heading east. Fern Cave is closed and protected by a metal gate and only open to visitors on guided tours.
Continue to follow the trail north for a short distance where it ends at a metal gate and dirt parking area for the north trailhead. This trailhead is located along the road that runs the length of the northern portion of the park.
Wildflowers, some juniper trees, and plenty of sagebrush, rabbitbrush, and the like.