Kaūmana Caves State Park

The Kaūmana Caves State Park is home to the Kaūmana Cave, an old and inactive lava tube whose ceiling collapsed, opening it up for the curious and the brave.

The Kaūmana Cave isn’t the most-visited tourist destination; they're a bit rougher than its well-known cousin, the Nāhuku-Thurston Lava Tube in Volcanoes National Park. The floor isn't evened out but was left exactly as it looked when the lava left it; an ankle-twister. There isn't any electric light; the only light comes from the outside and quickly disappears the deeper you go into the lava tube. If you bring a headlamp, the algae that grows on the walls of the lava tube will put on a beautiful show. It looks as if the walls themselves were emitting silver and gold light.

The Formation of the Kaūmana Cave

The lava tube that is nowadays known as the Kaūmana Cave was formed during Mauna Loa eruptions that, in 1881, threatened Hilo (Jim Kauahikaua, USGS). Lava tubes develop when pahoehoe lava is present, and there are two ways they can form. When the lava is streaming through a channel, the buildup of cooled-down lava can roof over the channel and create a lava tube. When the lava flow isn’t enclosed in a channel, usually further away from the vent, a lava tube can develop as the surface of the lava cools quickly while the center remains molten and continues to flow.

During the 1881 eruption, it is estimated based on eyewitnesses that lava flowed through the Kaūmana Cave at roughly 40 miles per hour (Jim Kauahikaua, USGS). If you look closely at the floor of the tube, you can see leftover lava that solidified there as well as a much smaller lava tube that branches off under the floor some 50 feet from the entrance.

State Park vs Private Property

Only parts of the Kaūmana Cave are for the public, the rest is privately owned by the people who own the grounds above the lava tube. The parts with restricted access aren’t easily identifiable, however, as you’d need permission by the owner to cross into these spaces, it is advisable to turn around and return to the entrance sooner rather than later.

North vs South

You can visit both the north part and the south part of the lava tube. Most people go to the north cave and stay around the entrance. The north portion is bigger and you can go much deeper into the lava tube there.

However, the south portion offers much more solitude. There’s a shelf of lava that seemingly cuts off the way; you can scoot under it and it will bring you to an open chamber where you can stand. The ceiling there is much lower and allows for a closer inspection of the formations left behind by the lava as it slowly cooled, got thicker, and dripped from the ceiling. Please don’t scoot under the shelf unless you’re completely comfortable with it. It’s the only way back out so you’ll have to go through there again.

Safety

Another reason why a long venture into the lava tube might not be the best idea is the amount of risk that comes with cave exploring. From seismic activity to floods, there are more than one way a prolonged trip into the cave might prove fatal.

Bringing a jacket is a good idea, even if it's 100°F outside. The caves get slightly colder the further in you go but the air is still humid. In case of injury, having a jacket will make the wait for rescuers much nicer.

Bring appropriate footwear. The lava tube might look tempting as just a quick stop on the way back from/to Hilo, however, as said above, it can be quite the ankle-twister. It isn’t impossible to venture in wearing open-toed sandals, however, it could easily end up with a cut toe, a lost toenail, a twisted ankle, a broken leg, or a combination thereof. Sturdy shoes will allow you to explore further and stay safe.

Whether you’re going alone or with a friend, bring more than one source of light. Flashlights break, batteries run out, and daylight doesn’t reach deep into the cave. If you go far enough, you’ll find dark to which your eyes will not get adjusted, no matter how long you wait.

Don’t depend on cell service in case something goes wrong. You’re under the ground, it will be non-existent.