isle of eigg
Photo: Lee Frost/Getty Images
Nothing blows the mind quite like the curiosities dreamed up by nature. O takes you to 10 awe-inspiring and absolutely humbling wonders of our world.
The Isle of Eigg

This little island (pictured above) a few miles off Scotland looks ordinary enough, with a rugged coastline similar to that of the other 40 or so isles that surround it. What makes Eigg unique is the music it produces. As you run your hands through the sand at the Bay of Laig, you may hear high-pitched notes, like the sounds of some otherworldly string section warming up. The sand grains are pure quartz, highly rounded and of fairly equal size. In dry conditions, they can rub against each other in a way that produces instrument-like vibrations, resulting in the beach's mysterious song. —Arianna Davis

The Plitvice Lakes

Deep in the woodlands of Croatia's Dinaric Mountains is an enchanting valley populated by deer, wild boar, wolves, bears, and some 126 species of birds. But the valley's gems are tucked in its limestone bottom: 16 terraced lakes that cascade into one another, spilling over mossy ledges and plunging down canyon walls. (One thundering waterfall drops 230 feet.) Depending on sunlight and the season, and the mineral composition of the bedrock, the colors of the lakes shift from azure to green to gray. Visitors to this misty, fluid landscape can wander down wooden walkways that offer meditative views of flower-filled meadows, caves, crags, and pools clear enough to catch the eye of a fish. —Kristy Davis

Next: The most beautiful pool of bacteria you've ever seen (really)