1. The Enchanted River; Mindanao, Philippines
Running through the island of Mindanao in the Philippines, the Enchanted River (real name: Hinatuan River) is not only a beautiful body of water, but a stunning natural mystery — no one knows exactly where the river comes from. Although the river's source is undetermined, it is still a popular destination for swimmers and divers alike.
2. Abraham Lake; Alberta, Canada
The frozen bubbles that appear when Abraham Lake freezes over look beautiful, but could potentially be very dangerous. That's because the bubbles aren't air bubbles, but rather, methane bubbles, which wikipedia notes "may form explosive mixtures with air" due to methane's flammability.
3. Salar de Uyuni, Bolivia
The world's largest salt flat, Salar de Uyuni was created when a prehistoric salt lake in the region dried up. During the rainy season, the salt is coated in a thin layer of water (as the rainwater has nowhere to drain), creating a mirror effect that stretches across the flat and provides stunning images of the sky and clouds.
4. The pink lakes of Western Australia
Including Hillier Lake and the aptly named Pink Lake, the pink lakes of Western Australia get their color, it is suspected, from dyes created by the bacteria that live in the lakes or the presence of a high concentration of algae.
5. Green Lake; Tragöß, Austria
The Green Lake, or Grüner See, is located in the village of Tragöß, Austria and seems normal at first glance. However, that glance depends on what time of year you see the lake. During the frozen winter, the lake is mostly dry and becomes a popular spot for hikers in the region. However, when the temperatures rise, ice and snow on the nearby mountaintops begins to melt and fill the lake, covering up the grass, trees, and benches that had been visible only months before.
6. Lake Baikal, Russia
Located in Siberia, Lake Baikal is known for its stunning turquoise shards of ice that form in the cold of March. Caused by unequal pressure, structure, and temperature in the ice, these glass-like ice shards emanate from the surface in all their turquoise splendor.
7. Waitomo Glowworm Caves; Waitomo, New Zealand
Having been formed over 30 million years ago, the caves which make up the Waitomo Glowworm Caves system were first discovered by a local Maori chief in the late 1800s. The glowworms that line the surface of the caves are found exclusively in New Zealand.
8. Door to Hell; Derweze, Turkmenistan
After an accident at the site made by Soviet drillers in 1971, this cavern in central Turkmenistan, nicknamed the Door to Hell, has been burning ever since. Although the nearby village of Derweze has fewer than 500 residents, the cavern has become a well-known site for adventure-seekers looking to see the burning cavern for themselves.
9. Cave of the Crystals; Naica, Mexico
First discovered in 2000, the Cave of the Crystals (or Giant Crystal Cave) is filled with some of the largest natural crystals that have ever been discovered. Some of these crystals, composed of gypsum, have grown to more than 30 feet long. The cave is known for its extreme conditions, including almost 100% humidity and temperatures reaching 120 degrees fahrenheit.
10. Rainbow eucalyptus trees; Kailua, Hawaii (among other locations)
Although it may look as if someone has painted over these trees, the rainbow eucalyptus, or Eucalyptus deglupta, is a naturally occurring species. The bark begins as a chartreuse-green color, but as it ages, it picks up purples, reds, and oranges. As the layers of bark peel away, the array of colors are exposed.
11. Eternal Flame Falls; Chestnut Ridge Park, New York
Although there are many naturally occurring flames around the world, most are kept lit by certain natural gases. The rocks surrounding the Eternal Flame Falls, however, do not produce that gas, leaving scientists unsure how the flame continues to burn. The fire is said to have been lit by Native American peoples thousands of years ago.
12. Lake Kaindy; near Almaty, Kazakhstan
13. Caño Cristales; Meta, Colombia
During the brief period between the rainy and dry seasons in Serranía de la Macarena mountain range where the Caño Cristales is located, the water is inundated with a bright red plant called Macarenia clavigera, giving the river a reddish hue throughout. The unique color has led the river to be called "The River of Five Colors" (which also includes the colors of the sand, green plants, and other surrounding hues).
14. The Richat Structure; near Ouadane, Mauritania
Just over 30 miles in diameter, the Richat Structure, also known as the Eye of Africa, is a circular geological formation located in the midst of the Sahara Desert. How the shape came to be is still unknown, with theories ranging from an asteroid impact to natural processes of erosion, although the nearly precise circularity and placement of the rings has thrown many scientists for a loop.
15. Painted Hills; Wheeler County, Oregon
Formed over 35 million years ago by volcanic eruptions that led to the intermixing of ash, soil, minerals, and plants, the colorful stratified layers of the Painted Hills are known for their changes in color and pattern depending on the light, weather, and more. Visitors can hike and picnic around the hills while enjoying their changing hues.
16. Travertine pools; Pamukkale, Turkey
The small village of Pamukkale in Turkey is home to natural hot springs formed amongst terraces of travertine, a type of limestone. Although the pools were once open to swimming, officials have attempted to close them off to try to protect them from being destroyed.
17. The Wave; Coyote Buttes, Arizona
The Wave is part of the massive sandstones structures that comprise the Coyote Buttes ravine. The undulating shape was caused by wind and rain erosion over time, and only 20 visitors are allowed to walk through the area each day in order to prevent any damage.
18. Seven Colored Earths; Chamarel, Mauritius
These sand dunes located in the south of Mauritius are composed of many layers of different colored sands. The colors are the result of the earth's transition from lava to clay minerals. Although visitors are not allowed to climb on the dunes, there are viewing platforms to allow them to take in the beauty.