Nāhuku (Thurston Lava Tube) Trail

The Nāhuku parking area sits on Crater Rim Drive. It has 14 spaces, including two for oversized vehicles, and fills during busy periods. From the lot, use the marked pedestrian crossing; don't walk along the road. The paved trail heads into rainforest, with tree ferns crowding the path. Listen for native bird calls on this short approach. The forest is part of the visit, but this isn't a viewpoint hike: the lava tube is the reason to come.

The route takes you through about 600 feet of lava tube, then up a few stairs and back through the forest. The passage is mostly level, but several sections have a low ceiling, so watch your head. Visitors often report a wet floor and puddles; take your time where the surface is slick. The cave lights run on a schedule, so bring a flashlight if you might enter when they're off. Pets aren't allowed on park trails. For a photo, include the tunnel's curve and the roots hanging overhead; a little context shows more than a close-up of the rock.

Nāhuku formed about 500 years ago, when a river of lava near 2,000°F flowed through this area. As the outer lava cooled into a crust, it insulated the hotter flow beneath it. When the supply stopped or drained away, the hollow tube remained. Walking through it puts you inside the route that molten rock once took through the landscape.

Nāhuku means “the protuberances,” a name that may refer to lava drippings that once hung from the ceiling. Those formations disappeared after souvenir collectors began taking them following the tube's discovery in 1913. Local newspaper publisher Lorrin Thurston is credited with discovering the tube, which is why the English name stuck alongside Nāhuku. The missing formations are a good reminder to leave the rock and the roots alone.

Lava tubes on Hawaiʻi Island shelter life adapted to darkness, including specialized crickets, spiders, and microbial communities. You may not see any of them on a quick walk, but the cave is more than an empty tunnel. Keep to the path and don't touch the walls or hanging roots. Hawaiʻi Volcanoes protects these underground environments as fragile habitat, as well as remarkable volcanic features.