The “Eye of the Earth”, Mount Dinara Nature Park, Croatia.

This karst spring is named as such due to its strong resemblance to an eye with the various shades of blue and turquoise when seen from above. It is formed by a hole of unknown precise depth, but is said to be apparently more than 300 ft deep. This small body of water is the primary source of the Cetina River, the longest river in Dalmatia. The Cetina flows for about 65 miles from the northwestern slopes of Dinara, the highest mountain massif in Croatia standing at 6,000 feet above sea level, until it merges with the Adriatic Sea.