Sinkholes are formed when groundwater erodes the earth, creating pits that can be incredibly wide and deep. They're classified as natural disasters when they form suddenly, causing property damage and threatening lives. Some sinkholes, however, are stunning tourist attractions. The largest sinkholes on the planet form places where scuba divers can see the sea floor drop dramatically underneath them, adventurers can map out underground caverns, nature lovers can see unique wildlife, and intrepid hikers can descend into another world.
Also called the Heavenly Pit, the Xiaozhai Tiankeng in China is a staggering 2053 feet deep and 1762 feet wide. The edges of the sinkhole are vertical sandstone cliffs, and there is a thriving forest at the bottom. Xiaozhai Tiankeng is home to thousands of unusual plants and animals, including clouded leopards. Visitors can take a winding 2,800-step pathway to the ground or, if they're particularly daring, they can freefall. Base jumpers visit Xiaozhai Tiankeng for the ultimate thrill; by using a pulley system to the center of the sinkhole and then dropping to the bottom, deploying a parachute only a few hundred feet above the ground.
Just off the coast of Clarence Town in the Bahamas, the ocean floor suddenly drops 663 feet to a special underwater sinkhole called a blue hole. Dean's Blue Hole is a prime destination for divers of all skill levels. It's located near the shore in a sheltered bay with few large waves and great visibility, making it a relatively tame spot for beginners. As the deepest saltwater blue hole in the world, Dean's Blue Hole is also a popular place for professionals to try and break diving records.
This 400-foot-deep sinkhole in Texas is a great place to experience nature and history. Indigenous people consider the Devil's Sinkhole sacred, and there's evidence that it was once used as a burial site. Today, it's home to millions of Mexican free-tailed bats, which exit in vast swarms on warm evenings. Guests cannot enter the Devil's Sinkhole; they can look into the sinkhole and observe the bats via a platform constructed near the entrance.
Four massive sinkholes form an almost perfect circle on the summit plateau of Sarisariñama Tepui, a tabletop mountain in southeastern Venezuela. Sima Humboldt, the largest of the sinkholes, is 1150 feet wide and 1000 feet deep. Forests carpet the bottoms of the sinkholes and the surrounding mountain tops, the trees so numerous and close together that a person could be yards away from Sima Humbolt and not realize it. An expert guide is usually needed to keep visitors from getting lost. However, the view from the edge of Sima Humboldt is worth the trek. It's a breathtaking look into a stunning and truly unique natural world.
One of the most iconic dive spots in the world, the Great Blue Hole, is a circular sinkhole off the coast of Belize. Lighthouse Reef, which surrounds the Great Blue Hole, is home to sea turtles, parrot fish, and hammerhead sharks. Scuba divers can watch the stunning sea animals and, if they dare, sit at the edge of the abyss. Special equipment, training, and experience are needed to dive inside the Great Blue Hole safely, and experienced divers can explore underwater caverns filled with stalactites.
Tourists flock to Pueblo Mágico, Mexico for the Cave of Swallows, or Sotano de las Golondrinas. The narrow entrance of the sinkhole leads to a huge cavern just beneath the surface. Thousands of birds take shelter in the cave every night, including cave parrots, parakeets, hawks, and swifts. In the morning, these colorful tropical birds fly in winding circles out of the top of the sinkhole and into the surrounding forest; it's a breathtaking sight. Visitors can watch the birds from outside of the sinkhole, or they can rappel or rock climb into the cave with the help of trained guides.
The Chinese province of Guangxi is covered with limestone rock formations that are vulnerable to forming large sinkholes. One of the most famous is the Nongle sinkhole, an inclined collapse of nearly 400 feet. The steep cliffs and dramatic drop of Nongle are breathtaking, but what makes this sinkhole unique is what lies at the bottom. Adventurers who rappel to the bottom of Nongle find a narrow entrance to one of the largest cave chambers in the world; a cave hall called the Courtyard. A shallow lake at the bottom of the Courtyard sparkles in the light from the cave entrance. Ancient rock formations line the walls. The ceiling of this cave hall is so high above the ground that the Eiffel tower could fit inside it.
Cenotes are a special kind of geothermal sinkhole from the Yucatan Peninsula of Mexico that was sacred to Indigenous Mayan people. El Zacaton is one of Mexico's largest cenotes and the world's deepest water-filled sinkhole. Visitors to El Zacaton can swim in stunning blue waters, kayak out to the grassy floating islands that skim across its surface, or scuba dive into El Zacaton's underwater caverns and witness the colorful biomass that grows along its walls.
The Qattara Depression is a huge, teardrop-shaped sinkhole in northwestern Egypt where visitors can discover a truly unique ecosystem. The miles-long depression features waterfalls, reed swamps, salt marshes, Acacia groves, wetlands, palm trees, scrubs, and sand dunes. It is also home to many beautiful animals, including foxes, jackals, wild sheep, hares, gazelles, and even a small group of endangered cheetahs.
People come to Teiq Sinkhole in Oman for the waterfalls. Two perennial streams, or wadis, meet at Teiq Sinkhole and come thundering over the edge, falling 692 feet and then vanishing underground. During the rainy season, additional waterfalls form around the edges. Visitors can view these natural wonders from a constructed deck or trek down into Teiq Sinkhole to see the waterfalls up close. They can also explore Teiq cave, an impressive cavern with six natural chimneys.