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.