Hawaii is an archipelago-state formed by volcanoes; yet, these are the only lava tubes open and lit and reasonably accessible for the general public. Here's our favorite model demonstrating the latest fashion look in indoor rain gear. (Not a bad idea when the ceiling drips). Lava tubes are created when the top of a lava flow is cooled by the air...
...but the molten lava below continues to flow. Typically these are near the summit with the lava flowing downhill. Eventually the eruption stops and the remaining molten lava flows out through some opening below --- leaving empty tubes as seen here. These specific tubes were fed by the eruption which created the nearby Kilauea Iki crater. Once all the lava drained downhill, the area collapsed.
The tubes (about 500 years old) are named for Lorrin Andrews Thurston (1858–1931) -- a controversial figure who started a newspaper, played a huge role in getting Hawaii away from the monarchy and eventually to a US territory -- and loved volcano research. Like most things here, they have a Hawaiian name, Nahuku -- named after the rocks that protrude from the side.
The entire loop from the parking lot and back is an easy 20 minute walk. After a couple hundred yards, you enter the lit lava tubes. These go for about another 150 or so yards before a stairs exits back to the sunlight. Those so inclined (and armed with flashlights) are allowed to proceed into the unlit portion of the cave.
It is very dark here (and a lousy place for photographs). This doesn't keep the rain forest above from sending down roots.
Shorty after, the tube ends -- at least the part you can navigate with a flashlight as there is a very severe drop off.
But outside is a special ecological area. The National Park Service has wisely decided that since so many tourists are attracted to the tubes, they should try to do a little education. The entrance to the lava tubes is essentially a volcanic crater covered in a tropical rain forest. Here are the Hapu`u tree ferns that thrive anywhere in Hawaii and can grow to 20 feet tall.
These ferns also contain cores that can contain 50 pounds of starch. This attracts feral pigs who pretty well trash this place. Rangers kicked out the pigs and installed cattle guards to keep them out for good. (The pigs supposedly responded "moi!!) They are working on removing the alien plants to restore this place to what a real Hawaiian rain forest looks like. Unlike most rain forests, Hawaii's do not have a tree canopies and so their endemic species have little protection. Hawaii has the only tropical rain forests in the US (except for my backyard during Houston's mosquito season) and has more endangered species per square mile than anywhere else.
