Lava tube spelunking – who me?

Most people who visit Volcanoes National Park on the Big Island walk through Nāhuku Lava Tube. (It’s better known as Thurston Lava Tube, unfortunately named after one of the men who overthrew the Kingdom of Hawai‘i in 1893. I prefer to use its Hawaiian name.) But did you know that the Big Island is riddled with lava tubes? The largest discovered to date is the Kazumura Cave. So far, researchers have mapped more than 40 miles with many separate entrances. It is the longest lava tube in the world, though not the longest cave.

The girls (daughters/niece) and I were lucky enough to explore it. We stayed at a cozy B&B in Volcano Village, the Aloha Crater Lodge, where one of those entrances opens to this underground world. As part of their overnight package, Shannon and Dan give tube tours to their guests, complete with equipment.

Oh boy! We each picked out a hardhat, artfully covered with wild prints, fun patterns and bright colors. Armed with gloves, flashlights and our phones (cameras), we followed Shannon through the rainforest on their property, walking down-mountain to the tube entrance. Unlike Nāhuku where you just walk in, this opening was on the top of the tube.

“The first part is the hardest,” she advised helpfully as she turned on our hardhat headlamps. “Try crab walking down this steep slope – most guests find that the easiest way to get to the level with the ladder.” Crab walk on wet slippery rocks? Ladder? Umm, do I really want to do this? Once again, I bumped up against my comfort zone. But the girls cheered me on and I descended into the darkness of the underground. Actually, this was the only vertical portion of the tour. Once we got to the bottom of the ladder, the tube was almost flat – a comfortable walk.

From years of experience with other guests, Shannon knew the exact places and lighting conditions to obtain the best pictures. She even brought her own camera, because “phones don’t always capture the best picture.” Or in some spots, any, it turned out. We appreciated her emailing us some great shots of our adventure.

She explained how lava tubes form. As lava courses downhill, the outer edges cool first, eventually surrounding the hot liquid, which continues to travel within the now insulated tube. When the source of the lava stops pumping, the remaining lava moves through, leaving a smooth hardened shell tube. Eventually the forest recovers and new growth and a new forest floor form over the tube. Ohia trees are one of the first plants to grow on new lava, and in both this tube and the Nāhuku Tube in the park, one can see their roots growing and hanging from the ceiling.

Shannon also pointed out the little tips of lava on the ceiling called lava stalactites. These are not stalactites common in other caves. These tips form when new lava flows through a tube but does not fill the tube entirely. The heat of the lava semi-melts the ceiling lava and it “drips” down and hardens again. Then as the lava level rises and falls in the tube, it coats the initial drip shape. Once activity in the lava tube stops, they no longer grow. The longer ones are about three inches.

Partway along our underground walk, we saw chunks of the ceiling that had fallen down. The tour stopped a little further along at a point where the ceiling had collapsed leaving a pile of rubble blocking the path. That led to a nervous chat about the hazards of tube failures while underground: an extremely low probability but high negative consequences. Oh well, it would make for a spectacular obituary.

Shannon pointed out a unique mold that grows in these tubes. Combined with the water condensed on it, the mold reflected silver in the light of our headlamps and the flash of the camera. Too bad someone had damaged the mold by “writing” in it. Shannon said the graffiti was here when they bought the property years ago. Apparently, research is showing this mold to have cancer-fighting properties that could prove useful.

She showed us a vein of yellow sulfur where sulfur dioxide gases condensed during the cooling period. I wondered about the red colored lava rocks. In later Internet research I found that when the lava is exposed to the air, the iron in it oxidizes and forms the rusty color. So on the surface, the newest lava flows are black, turning to silver/gray over time and finally oxidizing to sienna.

But none of my later research told me who Kazumura was. Research papers provided many details about the five sections of lava tubes that were finally connected. Besides being the longest lava tube in the world, it is also the deepest, descending 3614 feet. But I could not find anything about the name. Shannon said a Mr. Kazumura first explored the tube. She met his granddaughter, who confirmed it. For that matter, none of the research sites mentioned the Hawaiian name of this lava tube. Someone needs to document the early uses and exploration of this cave.

On the walk back, we all bumped our heads a time or two on the low ceiling in parts of the tube. Love those hardhats – not just a fashion accessory. Then back up the ladder and a victory pose that Shannon captured from below.

We all agreed that it was well worth the time and effort. The whole thing lasted about an hour with maybe 30 minutes in the lava tube – the perfect amount of time underground and in the dark for my taste. But there are longer tours in the area for those more adventurous.

I wonder if this quick trip qualifies as spelunking. If so, I can check that off my bucket list. Truthfully, I’d have to add it first.

 

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