Pick up an inexpensive flashlight or headlight ($5–$15) at Walmart in Hilo or Kona before visiting this wilder, longer sibling to the more famous Nahuku (Thurston) lava tube in Hawaii Volcanoes National Park. As the sign warns, there are “no lights, no walkway” in this eerily fascinating set of caves formed by an 1881 lava flow that threatened downtown Hilo. Princess Ruth Keelikolani is credited with saving the town by praying to Pele to halt the lava. You can thank the county for maintaining the steep concrete stairs leading into the lava tube’s fern-lined “skylight,” where the larger right entrance offers a short loop trail and the left entrance leads to a more challenging (that is, watch your head) out-and-back path. Your flashlight will help you spot the lava that cooled fast enough to keep its red cover, and help you avoid stumbling over protruding roots. Wear long sleeves, since it can be cool and dripping, and sturdy shoes, to avoid slipping on the often-slick cave floor.