Hranická propast in Hranice

You're standing at the Hranice Abyss. It might look like just a big hole in the woods, but this is the deepest flooded pit cave in the world. Take a look at its shape. The opening is oval, roughly a hundred and ten metres long and fifty metres wide. This is karst country: limestone slowly hollowed out by water. Glance around, too, because you can spot more sinkholes like this in the ground nearby.