Nāhuku, the Thurston Lava Tube - Curiosity Trek - Hawaii

Nāhuku, the Thurston Lava Tube

We drove from the Kīlauea Iki Overlook around the other way to get to the Thurston Lava Tube, a huge tunnel left behind when the lava drained away.

Thurston Lava Tube
This huge tunnel was left behind when a subterranean river of lava drained away. An easy trail runs through the tube and a grove of giant ferns.
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Trail to Thurston Lava Tube - Curiosity Trek - Hawaii

Trail to Thurston Lava Tube

Trail to Thurston Lava Tube - Curiosity Trek - Hawaii

Trail to Thurston Lava Tube

First there is a short walk through giant ferns. We expected to see a dinosaur. It was raining, but not too bad and we were out of the wind.

Thurston Lava Tube Formation of a Lava Tube - Curiosity Trek - Hawaii

Thurston Lava Tube
Formation of a Lava Tube

Thurston Lava Tube
Formation of a Lava Tube

  • Most lava tubes form in molten pahoehoe lava flows.
  • Exposed to air, the top portion of a lava stream often solidifies and insulates the underlying fluid lava, which continues flowing beneath its hardening crust.
  • As eruptive activity diminishes the supply of new lava stops.
  • The molten lava then drains out like water from a shut off hose.

Trail Facts

This loop trail passes through a section of Thurston Lava Tube and returns to the parking area. Walking time is about twenty minutes. Some portions are moderately steep, but the trail is short. Exiting the tube, you will walk through part of a Special Ecological Area. This 25-acre unit of montane rain forest is a sample of native Hawaiian forest, free of destructive feral pigs and most non-native plants.

The fern-shrouded entrance leads into a well-lighted section of a prehistoric lava tube. As you walk this short segment you will follow the path of the molten river which formed the tube centuries ago. Ledges or benches such as these can be seen in Thurston Lava Tube. They form as the lava supply diminishes and mark different levels of lava supply through the tube.

Nahuku extends 334 meters beyond this point. You are invited to explore this undeveloped section of the lava tube where natural features have not been disturbed.

  • You will need a flashlight
  • Watch your footing
  • Be aware of low ceilings
  • Tread lightly on these fragile resources
  • Do not disturb toots or geological features
Entrance to Thurston Lava Tube - Curiosity Trek - Hawaii

Entrance to Thurston Lava Tube

Stairs into Nāhuku, the Thurston Lava Tube - Curiosity Trek - Hawaii

Stairs into Nāhuku, the Thurston Lava Tube

Entrance to Thurston Lava Tube - Curiosity Trek - Hawaii

Entrance to Thurston Lava Tube

Thurston Lava Tube - Curiosity Trek - Hawaii

Thurston Lava Tube

The lava tube was much larger than I expected!

Leaving Thurston Lava Tube - Curiosity Trek - Hawaii

Leaving Thurston Lava Tube

Roots hanging down into Thurston Lava Tube - Curiosity Trek - Hawaii

Roots hanging down into Thurston Lava Tube

I had no idea it was so huge. It did not rain on us underground.

Locked entrance to the rest of the lava tube - Curiosity Trek - Hawaii

Locked entrance to the rest of the lava tube

Locked off portion of Thurston Lava Tube - Curiosity Trek - Hawaii

Locked off portion of Thurston Lava Tube

Part of the lava tubes is out of bounds without permission.

Stairs from Thurston Lava Tube - Curiosity Trek - Hawaii

Stairs from Thurston Lava Tube

Stairs from Thurston Lava Tube - Curiosity Trek - Hawaii

Stairs from Thurston Lava Tube

Thurston Lava Tube Trail
Thurston Lava Tube can be accessed via an easy 15-minute loop trail. The paved trail begins with a steep descent into the rainforest, dense with towering green ferns. The trail then leads visitors to a pit crater where it is possible to enter the lava tube. Formed when the exterior of a lava flow cooled to a crust while the still-molten interior magma flowed out, the tube resembles a giant tunnel. Walk through the 600-ft winding passage takes about ten minutes. Signs posted along the trail provide information about plants and animals that can be seen in the area.
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On the way back, we stopped and read the signs we had passed on the trail through the fern forest.

Rain Forest - Curiosity Trek - Hawaii

Rain Forest

Rain Forest

You have entered a tropical rain forest. Ohi’a lehua trees form the forest canopy. Light-green fronds of hapu’u (tree ferns) dominate the understory. Often enveloped in clouds, dampened by mist, and drenched by rain – over 100 inches a year – this forest abounds with a diversity of live

Unlike tropical rain forests found on continents, where species occupy vine-filled canopies, most of Hawaii’s native species live on or near the forest floor. There they are especially vulnerable to alien invaders. Rangers fence out pigs and remove non-native plants from this and other imperiled habitats within the park. Such extra protection is vital to the continued existence of the only tropical rain forests in the United States.

Sounds of the Rain Forest - Curiosity Trek - Hawaii

Sounds of the Rain Forest

Sounds of the Rain Forest

Pause for a moment and listen. You may hear the songs of ‘apapane and ‘amakihi, two of Hawaii’s native honeycreepers, and perhaps an oma’o, a thrush found nowhere in the world but on this island. A strange whirring of apapane wings and the tinkling and trilling of Hawaiian crickets add to the rain forest chorus.

Joining the forest sounds are the calls of non-native birds that compete with and displace the natives. During the last 1,500 years, the human introduction of alien plants and animals – coupled with the destruction of habitat – have cause the extinction of innumerable species of Hawaiian birds, insects, spiders, and snails. How many more face the same fate within your lifetime?

Who was Thurston?

The Thurston Lava Tube was discovered in 1913 by Lorrin Thurston, the grandson of Asa and Lucy Goodale Thurston, two of the first Christian missionaries to Hawaii.

Lorrin Thurston was also a volcano enthusiast. In 1891, he bought the Volcano House hotel at the rim of Kīlauea. He expanded it before he sold to George Lycurgus in 1902.

Thurston was friends with Dr. Thomas Jaggar, an early volcanologist. He raised the money to fund the Hawaiian Volcano Observatory in 1912.

Thurston owned a newspaper and heavily promoted creating a Volcano National Park. Thurston was at Columbia with President Theodore Roosevelt. He was able to get support from Roosevelt, John Muir, and Senator Henry Cabot Lodge. Hawaiʻi Volcanoes National Park was formed in 1916.

When the Thurston Lava Tube was found, the roof was covered with lava stalactites, but souvenir collectors “picked” them. People used to believe stalactites grew back.

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