The river at Skocjan Cave

This is the river at Skocjan, as it pours out of a crack in the cliff on one side of a huge ravine. On the other side, it flows directly back into the rock. At one time, this whole river was underground. At some point in history, it basically opened up a huge sink-hole, several hundred feet deep and at least a mile across. Now the water gets to catch a glimpse of sunlight or starlight as it crosses the floor of the ravine, escaping from one cave just to enter another.