In the hills above the City of Hilo, near the approach to the inter-island highway known as “Saddle Road” which links East and West Hawaii on the Big Island, there’s a massive lava tube beside the road that goes unnoticed by most drivers.

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A portion of the tube’s ceiling collapsed many decades ago, creating entrances to two very different caves steeped in moss and broad-leafed jungle. The lava that once traveled through the underground passageway – which in some places is wide enough to drive a school bus through – came from Mauna Loa, one of the five Big Island volcanoes forming its landmass. That eruption dates back to the late-1800s, during a period of increased activity at Mauna Loa when lava flows spanned across the island and virtually reached Hilo Bay. Since then, much of the eruptive activity on the island has come from Kilauea Volcano, which is essentially an offshoot of Mauna Loa bursting through its eastern flank.

The main lava tube making up Kaumana Caves travelled nearly 25 miles underground before subsequent cave-ins. Most of the remaining cave system is inaccessible to visitors, and for good reason: rainfall higher up on the mountain slopes seeps into the caves and can flood sections, rendering them impassible. Most people who make the trip up Kaumana Drive in search of these formations aren’t professional or aspiring cave divers; they’re casual day-trippers, who are interested in the richly unique geology of Hawai’i Island and want an opportunity to get up close and personal with a towering, strangely textured tunnel of black lava rock. They’re people who aren’t afraid of the dark, are keen to get off the beaten path and don’t mind a bit of scrambling in order to experience something truly once-in-a-lifetime.

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A concrete staircase with hazard-yellow painted handrail leads down to a rocky landing, having brought explorers through what would have a century ago been the side of the intact lava tube. The landing is strewn with boulders leftover from the collapse, which have been thoroughly overgrown with a range of creeping vines and broad-leafed shrubs. From this glen of saturated sunlight and bright green, the two cave entrances stick out vividly; dark voids in the wall of jungle that beams of golden sunlight struggle to breach. Tall trees grow out of the tops of the caves in both directions, sending their strange tendril-like roots down through the lava and creating curtains of orange that dangle from the ceiling. Everything seems to be soaking wet, and the unmistakable drip of water on stone comes filtering in from all directions. 

Cave-goers have to choose to go left or right at the bottom of the staircase. The left section has a smaller opening with a shorter hike, and can sometimes involve scrambling over rocks or scaling the sides of small lava drifts. This section of cave ends with a pile of boulders from another collapsed area, and doesn’t seem to go far enough from the entrance to lose visibility completely. This means that external lights aren’t crucial for this section, although it’s still a good idea to bring them along in order to keep good footing.

Opting to go right, however, leads hikers on a much darker, dingier and longer route which zig-zags back and forth underground and shrouds visitors in complete darkness. This route is similarly precarious as the former, if not a little easier, and the air is muggier and more stagnant-smelling. After several hundred feet the cave walls close in a bit and it can get slightly claustrophobic, though the intrepid visitor, obviously equipped with good shoes, water, and a flashlight, can push on through this and enjoy exploring nearly two miles of lava tube which is still open to the public.

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One of the most interesting parts of Kaumana Caves is the rock formations; every imaginable texture, from smooth, ropey channels of lava to walls of patterned corrugated ridges to giant boulders of sharp, needle-like textures that look like beds of nails. At times the cave can seem a bit spooky; especially taken together the cold dank air, the darkness, the eerie sounds of water dripping and the sometimes menacing-looking lava formations. 

On the return trip, after being shrouded in pitch black for many minutes, hikers’ eyes have become accustomed to the dark and the entrance comes into view at first from very far off in a blinding cascade of light. Out of the darkness only tempered by the artificial beams of headlamps and flashlights, comes the familiar warm glow of natural light again. Hot breaths of fresh, humid air blow in from the entrance and reinvigorates weary hikers, helping to cut through the staleness of the cave. The path ahead becomes easier to see, and flashlight beams grow weaker and weaker as the entrance nears.

As this light filtering in grows stronger, the omnipotent dark green hue of Hawaii jungle starts to appear again, and the surrounding air temperature jumps about 10 degrees in one minute. Here you’ll sometimes see other groups of hikers strapping on backpacks and lacing up boots, preparing to make their own delve into this strange, rugged underground world.

A Chance to Experience The Raw Ruggedness of Hawai’i’s Volcanic Past

To be clear: Kaumana Caves is not the only easy-to-access lava tube open to the public in East Hawaii Island. It’s got some real competition from places like Thurston Lava Tube located within Hawai’i Volcanoes National Park. Thurston, however, is child’s play compared to Kaumana: its perfectly graded, well-lit tunnel of hanging lanterns pales in comparison to the insecure footing, lack of light and constant dripping of Kaumana. Simply put: Big Island has lava tubes to explore for every level of ability and interest, but for those wanting to experience a raw and unaltered piece of volcanic history and don’t mind a bit of scrambling, Kaumana is a highly underrated, once-in-a-lifetime experience lying along a stretch of deserted highway.

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That’s another plus about this destination: it seems to almost always be deserted. The parking lot across the highway that serves the cave complex is large enough to accommodate a dozen or so groups of cave-goers at once, but it seems to rarely have more than two or three cars parked there at a time. This is likely thanks to its isolation – it’s a bit of a drive to get to Kaumana Caves from downtown Hilo, which is ripe with many other, more easily accessible, attractions like its Farmers’ Market, Bayfront commercial district, Kamehameha Statue and Bayfront Beach Park. But what is sacrificed in convenience is made up for in a truly unique Big Island experience which has its own brand of patrons: outdoorsy visitors who jump gleefully at the sound of “lava tube caves” and don’t mind a rough hike.

This is a destination made for “lava tourists”. It brings visitors intimately close to the natural force which, over the course of millennia, created every bit of land that now comprises Big Island. It’s a highly sensory experience, too: the feel of the many different types of lava from sharp and brittle to smooth and hard; the smell of wet earth and swampy air; the sight of curtains of roots dangling in the darkness; and the muffled crunch of boots on shifting gravel which echoes off the cave walls with an eerie, muted tone. Snapping photos in the pitch black is often doomed to failure, so visitors usually congregate at the entrance and capture the spot where the darkness of the lava tube gives way to jungly daylight.


From Downtown Hilo, turn onto Waianuenue Avenue and follow it up the hill until it forks. Staying right here will take visitors to Wailuku River State Park and the world-famous sights of Rainbow Falls and Boiling Pots. Keeping left at the fork will bring drivers onto Kaumana Drive and lead to the approach to Saddle Road. Roughly three miles after the fork, a long gradual right curve in the highway will reveal the parking lot for Kaumana Caves on the left. Park here and carefully cross the highway, walking downhill along the shoulder for a minute before reaching the top of the staircase with bright yellow handrail. There’s a restroom facility located here beside the top of the staircase, with a handful of picnic tables available for day-use.

It is essential to bring headlamps, flashlights, extra water and proper footwear on a trip to Kaumana Caves. DO NOT ATTEMPT THIS HIKE IN FLIP-FLOPS. Although the left portion of the lava tube can more or less be traversed without additional lights, the right portion absolutely requires it. It’s even wise to bring a backup headlamp and extra batteries, too, since getting halfway through the cave only to have your lights go out unexpectedly is a potentially dangerous situation. So come prepared, wear shoes with toe and ankle support, and make sure everyone in your group feels physically able to make the trip out and back again