Upper and Lower Lake (Plitvice Lakes, Croatia)

Plitviče Lakes is one of Europe's most amazing natural wonders. There are waterfalls interspersed throughout the park and CLEAR, blue water. The bottom of the lakes--and any trees that happen to fall into them--are calcified, making the blue of the water reflect all the more off of the surface above. No muddy-bottomed lakes here! I have never been anywhere else quite like it in my travels.