What does the inside of a lava tube look like? Find out on a trek that goes deep within the cave-like structure of hardened lava formed centuries ago by Hawaii's Kilauea volcano.
Treks to the Puapoo lava tube at Hawaii Volcanoes National Park will open to the public this year only in celebration of the National Park Service centennial. The park is near the southern end of Hawaii Island, 30 miles from Hilo.
The three-hour treks begin deep within a rain forest and a 15-foot descent by ladder into the tube formed as molten lava cooled.
Once inside, the only light in the tube comes from flashlights and headlamps as visitors hike over rocky, uneven terrain. For a 25-foot stretch, people need to crouch beneath a ceiling just 4 feet high.
The elevation changes by 500 feet during the four-mile walk.
Hikes are offered once weekly, led on an alternating basis by park rangers and guides from the Friends of Hawaii Volcanoes National Park.
Each tour is limited to 12 people, and participants must be at least 7 years old.
The Puapoo adventure costs $30 for adults and $25 for children ages 7 to 12. Reservations must be made at least one week in advance.
Participants must wear appropriate clothing (loose-fitting hiking pants or shorts and tops, hiking boots). Helmets with headlamps, flashlights and gloves are provided.
The Friends group also offers a longer, more intensive experience through its Wild Caves Exploration Institute. Through June 1, the introductory price is $150 for adults and $75 for youths.
The Puapoo tours will be offered only through the end of 2016 to help preserve the lava tube's fragile ecosystem.