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 ...

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.

The 24th and final Piece of Heart, coincidentally, is located on Death Mountain -- and you can only ... after heading south from the lava-filled room with all the connective pipes, you'll end ...

It includes Geomunoreum, regarded as the finest lava tube system of caves anywhere, with its multicoloured carbonate roofs and floors, and dark-coloured lava walls; the fortress-like Seongsan ...

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.