Lava tubes, cavities in the earth once filled with flowing lava, are the principal attraction of northern California’s Lava Beds National Monument, which boasts the greatest concentration of them in the United States. Reaching as wide as 60 feet in diameter, Skull Cave is one of the area’s largest lava tubes and offers one of the easiest caving adventures in the park. Highlights include a dramatic entrance, a natural bridge, and icy floor at the end of the cave.
To reach Skull Cave, bear northwest from the Lava Beds Visitor Center on California Route 10 for 1.3 miles, then take a right onto the paved Lyons Road. Continue to the end of the road, where there is parking for the Skull Cave hike and nearby Lyons Trail.
The descent into Skull Cave begins with a staircase heading down into a collapsed section of what was once a “master tube.” This underground channel was the principal highway for lava flowing through the Modoc Crater Lava Tube System; today, the tube is largely a jumble of charcoal-colored basalt, remnants of the old cave roof.
Bearing northeast, the trail descends deeper, aiming for the wide aperture of Skull Cave. The cave was named by 19th century spelunker E.L. Hopkins, who reportedly found a large collection of animal bones, including two human skeletons, inside the cave.
About 50 yards from the start, the Skull Cave Trail zig-zags through the entrance, then hugs the right side of the lave tube as the grade levels out. Once inside, the temperature drops considerably. About 1/10 mile from the trailhead, now in full darkness, you will reach a flight of stairs that brings hikers down to the lower level of the cave, passing directly under a natural bridge.
The hike ends at the ice-covered floor of the lower level, situated at the bottom of the stairs. Once part of the cave tour, visitors are now barred from stepping onto the ice and must instead view from behind a metal grate.
Once complete—you won’t want to stick around for long in the sub-freezing temperatures—return the way you came, exiting back out into daylight. Allot about 20-30 minutes for this round-trip hike in one of Lava Beds’ easiest caves.