With a central cavern measuring 350 by 215 by 430 ft, the 10 million year old Grotta Gigante in northeastern Italy is the second largest cave in the world open to tourists. The 10 million year old cave was first explored in 1840 by a spelunker hoping to find a water source at its bottom, but, alas, the river that carved the cave had left it 3 million years prior! The elusive "disappearing" Timavo River enters the ground near the mountains and exits near the sea, its underground course through the carbonates of the Karst Plateau still largely a mystery. Read more →