In central Croatia, not far from the border of Bosnia and Herzegovina, one finds Plitvice Lakes National Park. This UNESCO World Heritage Site is prized for its 300 square km of radiant natural beauty. Formed over millenia by the confluence of above-ground and subterranean rivers, the interaction of water with limestone, moss, algae, and bacteria forms 16 surface lakes so crystal-clear that their basins are visible from the surface.
Of the over 1 million people who visit Plitvice Lakes National Park every year, not one is allowed to swim — and with good reason. The presence of even the smallest amount of organic matter could disrupt the natural balance of the lakes, rendering them polluted.
Viewing the lakes and surrounding waterfalls, one cannot help but marvel.