Lava tubes are formed when smooth a’a lava flows through a channel, then crusts over. The still-molten lava underneath keeps flowing until the source stops, and it drains out, leaving a long tubelike cave.
We were lucky in that there were very few other tourists there at the time. (It was the first week of April, which isn’t exactly the height of Hawaii’s tourist season.) The Thurston tube is famous partly because of its size, and partly because it’s very easy to get to. It’s less than a quarter-mile walk from the road.
I decided to use ambient light as much as possible here. Unfortunately, I left my compact tripod in the car. It was already late in the afternoon, and I wanted to get to the coast while there was still light, or else I would have gone back to get it. So I braced the camera against the walls as well as I could, often getting diagonal photos—and of course getting ghost images of the other people walking through.
The trail runs through a long section of the tube, then out through a break in the side. The tube continues several hundred more feet, but it’s gated off with a sign warning you to bring a flashlight.
Now the lava tube itself isn’t the only amazing thing. Hawaii is full of microclimates. Remember what the caldera a few miles away looked like:
The Thurston tube is in an actual rain forest with giant ferns and everything!
Note: This visit to Kilauea was Thursday, April 7, 2005.
Update: I’ve posted higher-res copies of the photos to a Flickr album.