This massive lava tube from an 1881 Mauna Loa eruption sits tucked away on Kaumana Drive in a quiet Hilo neighborhood — most tourists never find it. Walk down the stairs into this fern-draped skylight opening and you've got two directions to explore: the left tube is perfect for families, a straightforward 30-minute walk that emerges at private property (just turn around there). The right side is where it gets wild — deeper, more technical, with crawl spaces and multiple branches that could keep you exploring for hours. The cave stays naturally cool with an eerie beauty created by roots hanging from the ceiling. It's completely wild and unimproved except for those entry stairs, which means real adventure but also real risk from loose rocks.
💡 Insider Tip
Bring headlamps, not just phone lights — you'll want both hands free and proper illumination for the full experience. Someone spray-painted arrows in the right cave to help navigation, but ignore the silly 'GO BACK' warnings halfway in.
Daylight hours (cave is dark inside)
Free
Small lot on Kaumana Drive
Anytime — it's cool and dark inside regardless
