National Geographic : 2017 Jun
A choose-your-own-adventure section of Kipuka Kanohina splits into three tunnels, which will narrow as cavers go deeper. Navigating lava rock can be perilous. “ The texture,” says one caver, “is like Velcro,” c apable of tearing clothing and cutting skin. There are also dangers overhead: Chunks of sharp lava can break off and fall from the ceiling.