//
Photo: Radim Holiš, CC BY-SA 3.0 cz via Wikimedia Commons
The deepest flooded pit cave in the world, it is a karst sinkhole. The greatest confirmed depth is 519.5 m (1,704 ft), of which 450 m (1,476 ft) is underwater.
Hranice Abyss is the deepest flooded pit cave in the world. It is a karst sinkhole near the town of Hranice, Czech Republic. In 2020 a scientific expedition revealed that the lowest reaches are sediment-filled and it was speculated that the sinkhole was formed by upwelling hot acidic water. The greatest confirmed depth is 519.5 m (1,704 ft), of which 450 m (1,476 ft) is underwater.
© OpenStreetMap contributors
An important archaeological locality. One of the possibilities to explore it is an 8-km/3-hr informational hike, starting at a Mammoth statue.