Hawaii’s lava tubes are concentrated on the Big Island (Hawaiʻi Island), where active volcanism has been building cave systems for hundreds of thousands of years. The most famous and accessible tubes are in and around Hawaiʻi Volcanoes National Park, but you can also find them on Maui and other islands. Here’s where to go, what to expect, and how these remarkable caves formed in the first place.
Kazumura Cave: The World’s Longest Lava Tube
Kazumura Cave on the Big Island is the longest mapped lava tube on Earth, stretching more than 40 miles along the flank of Kīlauea volcano. It’s also the deepest. Though the roof is never more than a few dozen yards below the surface, the cave drops 3,613 feet in elevation from its upper entrance midway up the volcano to its terminus near the coast. In places it’s the size of a subway tunnel; in others, you’re crawling.
Kazumura is not a walk-in tourist cave. Access is through private guided tours that take small groups into select sections. The cave sits on a mix of private and conservation land, so you can’t simply show up and enter. Tours typically last two to three hours and range from easy walking passages to more strenuous scrambles over rough lava rock. If you’re looking for a genuine caving experience rather than a paved walkway, this is the one.
Nāhuku (Thurston Lava Tube) in Hawaiʻi Volcanoes National Park
Nāhuku, commonly called the Thurston Lava Tube, is the most visited lava tube in Hawaii. It sits inside Hawaiʻi Volcanoes National Park, a short hike from the parking area near Crater Rim Drive. The tube is lit from 8 a.m. to 8 p.m., making it easy to walk through without specialized gear, though bringing a flashlight is a good idea if you visit outside those hours or want to explore the unlit extension at the far end.
The walk starts with a descent through a lush tree fern forest before you duck into the tube’s arched entrance. The paved passage runs roughly 600 feet and is tall enough to walk upright through most of it. Parking fills quickly, especially midday. If the lot is full, the National Park Service recommends using the Kīlauea Iki Overlook lot about half a mile away or returning at a less busy time. Keep in mind that Kīlauea is an active volcano. Eruptions can trigger temporary closures across the park, including road access to Nāhuku, so check park conditions before you go.
Other Caves on the Big Island
Beyond Kazumura and Nāhuku, the Big Island has dozens of known lava tubes scattered across its volcanic landscape. Kaumana Caves, just outside Hilo, is a free county park where you can explore two branches of a tube formed during an 1881 Mauna Loa eruption. The entrance is a collapsed skylight with a steep staircase leading down, and the interior is unlit and unimproved, so you’ll need flashlights and sturdy shoes.
Several smaller commercial operations on the Hilo and Kona sides offer guided tours of tubes on private land. These vary in difficulty from flat, easy walks to more adventurous crawls. Because many of these caves sit on private property, access changes frequently. Checking availability before your trip is worth the effort.
Lava Tubes on Maui
The Hana Lava Tube, also called Ka’eleku Caverns, is the best-known tube on Maui. It’s located near the town of Hana along the famous Road to Hana. The cave is on private land and normally operates as a self-guided tour. However, it is temporarily closed while the government conducts an archaeological inventory survey, with no reopening date announced. If you’re planning a Maui trip around this cave, confirm its status beforehand.
How Lava Tubes Form
Lava tubes are created by slow-moving pahoehoe lava, the smooth, ropy type common in Hawaiian eruptions. When a river of lava flows downhill, the surface cools and hardens into a solid crust while molten rock continues moving underneath. Over time, that crust thickens into a roof. When the eruption slows or stops, the remaining lava drains out, leaving behind a hollow tunnel.
The process happens in several ways. Sometimes the crust grows inward from the edges of a lava channel until it meets in the middle, like ice forming across a river. Other times, floating plates of cooled rock merge together on the surface. Overflow from the channel can also build up levees that arch over the stream and solidify. Which mechanism dominates depends on flow speed, temperature, and the slope of the terrain. The result is the same: a natural pipe that can carry lava for miles with very little heat loss, which is why tubes are so efficient at extending lava flows far from their source.
Sacred Sites in Hawaiian Culture
Lava tubes hold deep significance in Native Hawaiian culture. For centuries, Hawaiians used these caves as burial chambers, placing the bones of their dead inside. The caves are considered kapu, or sacred, because Hawaiians believe a person’s mana, their life energy, remains in their bones long after death. Disturbing these sites is a serious cultural violation.
In Hawaiian tradition, Pele, the goddess of volcanoes, created many of these caves through simultaneous acts of creation and destruction. Kazumura Cave, for example, is linked directly to Pele in Native Hawaiian folklore. When visiting any lava tube in Hawaii, staying on marked paths and leaving everything as you found it is both a legal requirement and a matter of cultural respect. Some caves are closed to the public specifically because they contain burial sites or other culturally sensitive material.
Unique Wildlife Inside the Tubes
Hawaii’s lava tubes aren’t just geological features. They’re ecosystems. Because the islands are so isolated, cave-dwelling species evolved independently here, and several exist nowhere else on Earth. The most studied is a group of tiny planthoppers in the genus Oliarus, insects that have completely lost their eyes, wings, and pigmentation after generations of life in total darkness. These blind planthoppers feed on tree roots that penetrate the cave ceiling, and they communicate entirely through vibrations sent along those roots. About 85 species in this group are known across the Hawaiian Islands, with seven found exclusively in caves.
Hawaii also has endemic cave spiders, amphipods, and other invertebrates adapted to life without light. These species are extremely vulnerable to disturbance. Touching cave walls, leaving food scraps, or introducing contaminants can damage the delicate food web these animals depend on. Scientists have also flagged the potential threat of white-nose syndrome, a fungal disease devastating bat populations on the mainland. Research by the U.S. Geological Survey found that cave temperatures at higher elevations in Hawaii could support the fungus responsible for the disease. Biosecurity protocols, including not wearing clothing or gear previously used in caves where the fungus has been detected, help reduce the risk of introduction.
What to Bring When Visiting
For developed tubes like Nāhuku, you don’t need much beyond a flashlight and closed-toe shoes. For anything wilder, the gear list grows. The National Park Service recommends at least three light sources per person (a cell phone does not count), a helmet, knee pads, gloves, and shoes with good tread. Caves maintain cool, stable temperatures regardless of the tropical heat outside, so a long-sleeve layer is smart even on a warm day.
Lava rock is sharp and unforgiving. The footing inside undeveloped tubes is uneven, with ledges, loose rubble, and occasional drops. Wearing shorts and sandals into a wild lava tube is a fast way to end up with cuts and bruises. If you’re going beyond a paved tourist tube, treat it like a proper caving trip.