With a depth of 46 meters that stretches on for 310 meters underground, Dunmore Cave holds a masterpiece collection of cave architecture dating back more than a thousand years. As the largest cave in Ireland, Dunmore offers some astonishing calcite formations that are well worth the spelunking adventure to see. For cave exploring enthusiasts the world over, Dunmore should be listed as a bucket list item of special interest. The cave is also the site of a tragic incident. Human remains littered the passageways, thought to belong to the victims of a Viking attack in the year 928. It is believed that the Vikings massacred the group by driving them into the cave and then filling the cave with smoke, effectively asphyxiating their victims on the hot smoke.