Just up the mountain from Hilo town sits one of the lesser-visited geological formations of the area. Kaumana cave is a 25 mile long lava tube that is accessed via a skylight created when part of the cave ceiling collapsed more than a hundred years ago, leaving two gaping cave doorways exposed to the outside world.
This lava tube was created by a lava flow from Mauna Loa in 1881 that was advancing toward the city of Hilo. History tells us that Princess Ruth Ke’elikolani made the journey to Hilo from Honolulu and stood praying in front of the creeping molten rock asking the goddess Pele to spare the city. The flow stopped just 1.3 miles from downtown and today Hilo continues to stand, defeated by neither lava nor tsunami.
Lava tubes are formed when a surface flow begins to cool around the edges, forming walls on its sides which over time becomes a trough, and then a tube as the center stays hot and the outside crusts over. As more lava flows through this pipe the center remains hollow and can transport molten rock underground for dozens of miles before exiting at the surface far, far away. Because of Hawaii’s volcanic composition there may be thousands of undiscovered lava tubes scattered beneath the surface of the island.
Kaumana cave is just one example of the spectacular caving to be had on the island. Easily accessible, the cave is less than a ten minute drive from Hilo town. Parking is across the street and the place is usually empty. A concrete stairway descends from street level into the wide pit, which looks just like the surrounding area, but 20 feet lower. Two openings present themselves. To the right is the larger opening, with a cavernous space that tapers down to a skinny corridoor some 100 feet back before going dark. This room is a great place to sit on a boulder and enjoy the cave with plenty of sunlight. To the left is another entrance. This one has more twists, squeezethroughs, and variety, but it plunges into total darkness after about 30 feet. Either way, if you plan to venture past the limit of the sunlight you’ll need to bring a powerful flashlight.