The Hranice Abyss formed after the sinkhole, between 16 million and 14 million years ago, as water at the surface began percolating down through soluble rocks such as limestone. T ...

QUICK FACTS. Name: Hranice Abyss Location: Hranice, Czech Republic Coordinates: 49.53214473576795, 17.750610529720298 Why it's incredible: The cave is so deep, the world's tallest building could ...