Don't expect too much, but these two lava caves offer a mini adventure: pitch dark, sharply rocky, dripping wet, low in spots, mossy and thick with ferns. The left-side cave is bigger and longer. Essential equipment: flashlight (torch) or headlamp with full batteries, hiking shoes with grip, gloves and water. Generally empty, grounds are lackadaisically maintained and car break-ins can occur. To get here, head 3.5 miles up Kaumana Dr (Hwy 200); look for the sign on the right side.
These caves are part of a vast, 25-mile underground network of lava tube formed by an 1881 Mauna Loa flow. As the flow subsided, the edges of the deep lava stream cooled and crusted over. Then, after the hot molten lava inside drained out, hollow tubes or caves remained.