A couple of photos from Kaumana Cave a 2 mile long lava tube on the Big Island of Hawaii. Pitch black except for your flashlight and camera flash. In some places you are crawling on your stomach to pass through openings. If you ever visit the big Island there is much more to see than the typical tourist locations!
Marc
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Presumably these are old flows, with no danger to current hikers? When crawling through an opening, you don't feel like you could be trapped, or get lost? I see what looks like red stalactites in one photo. Any danger of one of those breaking off and hitting someone?

This flow is centuries old so there is little danger of volcanic activity, I did not touch the stalactites but they are very thin and pose little danger. There were however, every so often a piece of the ceiling laying on the floor which was concerning.
Marc

I've been to this location a couple of times. From my memory those are not stalactites, but roots from trees growing above the lava tube. There's not much possibility of getting lost. It's just one long tube with no real choice about which way to go.