10 of the Most Incredible Natural Phenomena to See Before You Die (or They're Gone)

If you couldn’t tell by its name, the Great Blue Hole is a giant underwater hole in the middle of Lighthouse Reef, 73 miles off the coast of Belize. Technically, it’s a sinkhole that formed as far back as 153,000 years ago, before sea levels were as high as they are today. After some glaciers danced around and melted, oceans rose and filled in the hole (very scientific explanation, no?). The near-perfect circle (wow) is 1,043 feet in diameter and 407 feet deep, giving it a dark navy hue. Not only is the Great Blue Hole a World Heritage Site of UNESCO, but it was also one of Jacques Cousteau’s top diving spots, so you know it’s legit. You’ve got to be an expert scuba diver to actually go down into the hole, but snorkeling on its edges is allowed (and frankly offers more colorful scenes of fish and coral due to the sunlight). But, if you want the best view? Hop on a helicopter for a visually stunning flyover tour.

In the mood for something savory? How about 4,086 square miles of salt? That’s how big Salar de Uyuni, the world’s largest salt flat, is. Located in southwest Bolivia, near the Andes Mountains, this bright white, flat expanse looks like a desert but is actually a lake. Let us explain: Roughly 30,000 years ago, this area of South America was covered in a giant saltwater lake. When it evaporated, it left behind a thick, salty crust on the earth’s surface. Today, the flat produces salt (duh) and half the world’s lithium. During the rainy season (December through April), smaller surrounding lakes overflow and cover Salar De Uyuni in a thin, still layer of water that reflects the sky almost perfectly for a sublime optical illusion. If your goal is seeing as much of the flat as possible, head out during the drier season (May through November). Tours are available from starting points in both Chile and Bolivia. Just be sure to hydrate.

Nestled between Eastern Europe and Western Asia is the Republic of Azerbaijan, home to hundreds of volcanoes that regularly spew goopy, gray mud. These short volcanoes (10 feet tall or so) dot the desert landscape throughout Gobustan National Park (another UNESCO World Heritage site) near the Caspian Sea. Since eruptions are caused by gases escaping through the earth instead of magma, the mud tends to be cool or even cold to the touch. Don’t be afraid to join in if other visitors bathe in the mud, which has been used for skin and joint ailments and in pharmacology. Certainly not FDA-approved, but when in Azerbaijan, right?

After taking a dunk in Azerbaijan’s volcanic mud, we recommend bathing in glow-in-the-dark ocean water on the tiny tropical island Vaadhoo. Visitors can see the ocean shores light up at night due to tiny phytoplankton in the water. These bioluminescent buggers emit a bright light when the water around them hits oxygen (aka, waves hitting the beach) as a defense against predators. Lucky for us, this creates a naturally occurring liquid glitter we can swim in. Consistently ranked one of the top vacation spots in the world, the Maldives is also increasing in popularity because it’s sadly disappearing. About 100 of the 2,000 islands that make up the Maldives have eroded in recent years and water levels continue to chip away at many of them. Might be time to move this item up on your bucket list.

There are a bajillion beautiful waterfalls to see around the world before you die (or they dry up), but Blood Falls in east Antarctica is one of a kind for its blood-like, well, flow. Explorers discovered the red-hued river flowing off the Taylor Glacier in 1911, but it wasn’t until last year that we figured why exactly the water was red. Turns out, there’s iron in the water (from an underground lake) that oxidizes as it hits the air. It’s tricky to get to Antarctica, yes, but certainly worth the trip to see this five-story-tall phenomenon in person—especially since it’s impossible to tell how long Antarctica’s current ecosystem will be around.

If you’re dying to see naturally occurring red water but aren’t partial to Antarctica’s chill, Lake Natron in Tanzania is a hot option. Salty water, high alkalinity and shallow depths pretty much make Lake Natron a warm pool of brine only microorganisms could love—and love it they do. During photosynthesis, the lake’s microorganism population turns the water a bright reddish-orange. Since the lake is no fun for large African predators, the setting makes a perfect annual breeding ground for 2.5 million lesser flamingos, a species listed as “near threatened.” Lake Natron is their only breeding spot, which means potential plans to build a power plant on its shores could destroy the lesser population. There is also talk of building an electric plant in Kenya, near the lake’s primary water source, that could dilute Natron and upset its delicate ecosystem. So get there quickly. And kiss a flamingo for us.

This entry on our list isn’t so much about a particular location as it is about what happens there. Every fall, monarch butterflies begin a 2,500-mile migration from Canada to Mexico. Over 100 million butterflies travel together, turning the skies orange and black, down through the U.S., before settling in central Mexico. Once they’ve reached hot spots like the Monarch Butterfly Biosphere Reserve, about 62 miles outside Mexico City, they nest, essentially taking over every square inch they can find. Pine trees literally sag with the weight of hundreds of butterflies latching onto branches. Visiting in January and February is best, when the populations are highest right before the butterflies head north in March. Fun fact: The monarchs that make it back to Canada in spring are the great-great-grandchildren of the butterflies that lived it up in Mexico over the winter. Unfortunately, the monarch population has dwindled significantly in the past 20 years, due in part to shrinking milkweed availability, the monarch’s favorite food.

For spelunking enthusiasts, Jeju Island is a must-see. Located 80 miles off the southern tip of South Korea, the 1,147-square-foot island is essentially one big dormant volcano with hundreds of tinier volcanoes around it. Most notably, however, is the Geomunoreum Lava Tube System below Jeju’s surface. An enormous system of 200 underground tunnels and caves formed by lava flows between 100,000 to 300,000 years ago provide ample space to pretend you’re Lara Croft. Did we mention many of these caves have multiple levels? And there’s a lake underground, too? With some of the longest—and largest—caves in the world, it’s no surprise this is another UNESCO World Heritage Site on our list.

There’s really no other way to describe these mountains than as orange sherbet rocks. The Zhangye Danxia Landform Geological Park is mile after mile of brightly colored, striped hillside made of sandstone and mineral deposits. Formed over millions of years as tectonic plates shifted and pushed underlying rock to the earth’s surface, this—you guessed it—UNESCO World Heritage Site is a lesson in both geology and art. Similar rainbow-colored mountains can be found in Peru, but this range in China’s northern Gansu province is easier to hike and offers equally stunning views of red, orange, green and yellow stone. Visit between July and September for optimal sunshine and light.  

Volcanic activity heats water below the earth’s surface, creating either boiling geysers or calm, steamy, natural hot tubs. We’ll take option #2. While there are many places to experience the soothing properties of hot springs (Blue Lagoon, Iceland; Khir Ganga, India; Champagne Pool, New Zealand), and we highly recommend you get to at least one in your lifetime, the Cascate del Mulino springs in Saturnia, Italy, caught our attention. Formed naturally by a sulphurous waterfall carving its way through rock, this sprawling landscape of pools clocks in at 98° F and is constantly flowing. The water is said to have healing properties thanks to sulfur and plankton swirling around. The best part? Cascate del Mulino is free to swim in and open 24/7. If you’re in the mood for a more upscale Tuscan hot springs vacay, stay at the Terme di Saturnia, a spa and hotel situated closer to the hot springs’ source.