Four Portuguese cavers have been rescued after a sudden flood trapped them in a cave network in Cantabria, northern Spain. The four, from a climbing club in Porto, went missing on Saturday in the ...

Getting trapped or lost here is extremely likely. The narrow, cramped passageways and winding tunnels are just part of what ...

For some unusual sights, try these 7 underground tourist attractions around the world, from caves to wartime tunnels ...