Centuries of eruptions on the Big Island have created hidden networks of passages beneath volcanoes. In December 2016 a large lava delta formed by Kilauea volcano sank into the sea, exposing the ...

Approximately 700,000 years ago when molten rock erupted from a vent in nearby Hart Prairie, the mile-long Lava River Cave was formed. Today, visitors can explore the cave's cool, dark expanse by ...

About 5 miles from downtown Hilo, on Kaumana Drive, you'll find the Kaumana Caves. Originally formed in 1881 by lava flow from Mauna Loa, the caves are now accessible to visitors via a metal ladder.

The Canary Islands not only boast the third largest volcano in the world, but also the largest natural underwater lava tunnel ... and a blend of dry and submerged cave sections.