Two interesting cave stories in the news recently:
Hoard of Iron Age coins found in Dovedale cave
http://www.ashbournenewstelegraph.co.uk/Treasure-hoard-Dovedale-cave/story-21335566-detail/story.html#bAgEu1lbZixFqW8X.99
See The Claustrophobic Underground Tunnels Left Over From The Vietnam War.
http://www.rediscoverit.net/see-the-claustrophobic-underground-tunnels-left-over-from-the-vietnam-war/?utm_source=ob&utm_medium=cpc&utm_campaign=See-The-Claustrophobic-Underground-Tunne