Zelenci Nature Reserve, Slovenia

© Andrey Danilovich/Getty Image

Revealing nature's turquoise gem. Zelenci Nature Reserve, Slovenia

Experience nature's palette at its colorful best, where visitors can witness a breathtaking natural water reserve at the meeting point of three countries. At Zelenci Springs - where Italy, Austria, and Slovenia meet near the Kranjska Gora region in Triglav National Park - multiple springs combine to form a crystal-clear, aquamarine lake, a source for the Sava Dolinka River, which feeds into the Danube River.

Covering an area of only 1,200 meters in length and 150 meters in wide, the Zelenci Nature Reserve was declared an ecological site due to its vast array of plants and wildlife in 1992. Fascinating fact: If a visitor peeks closely into the lakebed, they'll spot exquisite springs that resemble underwater volcanoes beneath the surface. Despite any harsh weather conditions prevailing above ground, underground water temperatures stay around 5 degrees Celsius, always flowing but never freezing over, even in winter.