14 Amazing Sinkholes

Landscape with a large hole in the center
Photo: Menahem Kahana/AFP/Getty Images

Some of the world's most famous sinkholes are seemingly endless pits that swallow trees, cars and entire buildings — dangerously altering the landscape. Others fill with water, becoming popular swimming holes and offering unique photo opportunities.

In the strictly geological sense, sinkholes occur when water erodes solid bedrock, creating an underground cavity that collapses inward. However, the term can be used in a broader sense to describe any sudden slump of the Earth's surface. Regardless of how you define them, these massive holes — like this one in an abandoned tourist resort on the Dead Sea in Israel — capture our curiosity with the mysteries of their bottomless depths.

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The Great Ravenna Boulevard Sinkhole

Photo: Seattle Municipal Archives/Flickr

One of the largest and most expensive sewer collapses in the United States occurred on the night of Nov. 11, 1957, in Seattle. The sewer trunk collapsed 145 feet below the street, but the massive sinkhole that resulted was just 60 feet deep. Repairs took two years to complete.

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Speedway sinkhole

Photo: Charlotte Motor Speedway

A sinkhole formed in the infield of the Charlotte Motor Speedway in North Carolina in September 2010 when a 30-year-old drainpipe deteriorated 35 feet underground. The speedway was built atop an old landfill, and heavy rains contributed to the underground collapse.

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The Great Blue Hole

Photo: Globe Guide Media Inc/Shutterstock

The Great Blue Hole is a large underwater sinkhole off the coast of Belize that's more than 1,000 feet wide and 400 feet deep. It formed as a limestone cave system during the last ice age when sea levels were lower, and the caves flooded as the planet warmed and sea levels rose.

Jacques-Yves Cousteau made the site famous in 1971 when he declared it one of the top 10 scuba diving sites in the world, and today it is a World Heritage Site.

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Cenote Ik Kil

Photo: Subbotina Anna/Shutterstock

Cenote Ik Kil (cenote means "natural well" in Spanish) is a large sinkhole on Mexico's Yucatan Peninsula that's sacred to the Mayans. The peninsula's unique composition of porous limestone has resulted in several of these water-filled sinkholes, but Cenote Ik Kil is one of its most famous.

The hole is 90 feet deep, adorned in tropical vegetation and filled with clear blue water that Mayan royalty used for both relaxation and ritual sacrifices. This year Red Bull held its Cliff Diving World Series at the sinkhole — divers leapt from the cenote’s surface and reached speeds of 40 mph before entering the water.

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Neversink Pit

Photo: Peter Pham/flickr

Neversink Pit is a limestone sinkhole in Alabama, and it’s one of the most-photographed sinkholes in the world because of its beautiful fern-covered ledges and waterfalls. The hole is about 40 feet wide at the top, but it expands to 100 feet at its bottom, which is 162 feet from the ground. Neversink is home to bats and several rare and endangered fern species.

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Montezuma Well

Photo: Alexey Stiop/Shutterstock

Montezuma Well is located in Arizona’s Montezuma National Monument Park. The sinkhole was formed during prehistoric times when a limestone cavern collapsed, and today it’s 365 feet wide and 55 feet deep.

Some 1.4 million gallons of water flow through the sinkhole each day from underground springs. The water of Montezuma Well is highly carbonated due to high levels of carbon dioxide, and the water contains very little oxygen and high levels of arsenic so it can’t support fish.

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Devil's Den

Photo: Eric Beach/Wikpedia

Devil’s Den is a fern-draped sinkhole in Williston, Florida, that is fed by underground springs. The water averages 72 degrees Fahrenheit, and on cold winter mornings, steam can be seen rising from the ground — thus, early settlers named the pit Devil’s Den.

The sinkhole’s clear, warm water makes it a popular diving and snorkeling site, and visitors to the cave can see ancient rock formations, stalactites and fossil beds.

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San Antonio, Texas

Photo: San Antonio Fire Department/Facebook

A large, ruptured sewer line plus several inches of rain may have been the cause of a sinkhole that opened up in southwest San Antonio on Dec. 4, 2016. The sinkhole swallowed two cars, killing an off-duty sheriff's deputy and injuring two more people.

As firefighters worked at the site, a few collapses widened the sinkhole, exposing the rescue team to raw sewage.

"This is tragic and surprising," Chief Charles Hood of the San Antonio Fire Department told WOIA. "Someone is driving 40-50 mph and doing the things we do while driving like listening to music and you have the road fall out form underneath you. That's a very sad situation."

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Numby Numby

Photo: Oldbloke49/Wikimedia Commons

The Numby Numby sinkhole is located in Australia’s Northern Territory and is surrounded by high cliffs. An underground hot spring feeds into the pit, keeping the water a steady 90 degrees Fahrenheit. The water reaches a depth of about 200 feet almost immediately, and the sinkhole’s shallow waters along its edge are occupied by large lilypads.

The Australian Aborigines believed that Numby Numby was home to evil spirits.

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Guatemala City sinkhole

STR/AP.

The sinkhole that occurred in Guatemala City in June 2010 is unique because human activity — not nature — was the likely cause of it. A burst sewer pipe probably created the underground cavity, which is 60 feet wide and 300 feet deep, according to Sam Bonis, a geologist at Dartmouth College.

Guatemala City was built in a region where the earth is composed mostly of pumice fill from past volcanic eruptions. The ground isn’t solid rock and can be easily eroded when heavy rains occur, such as during Tropical Storm Agatha, which is when this sinkhole formed.

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Picher, Oklahoma sinkhole

Charlie Riedel/AP.

The Environmental Protection Agency calls Picher, Oklahoma, the “most toxic place in America,” and today the city is a modern a ghost town. Years of mining for lead and zinc has left the town full of sinkholes like this one. The roofs of some of the mines — unable to support the weight of the earth — collapsed, and now the former municipality is home to only giant chat piles and numerous massive sinkholes.

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El Zacatón

Wikimedia Commons.

The El Zacatón sinkhole is the deepest water-filled sinkhole in the world. It was long considered to be bottomless, but in 1997 NASA solved the pit’s mystery when it sent an underwater robot into the waters and found the depth of El Zacatón to be 1,112 feet.

The clear, blue water is highly mineralized and has a sulphurous odor, and it’s quite warm — averaging 86 degrees Fahrenheit. The sinkhole’s name comes from the free-floating islands of zacate grass that blow across the lake in the wind.

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Daisetta, Texas sinkhole

Dave Ryan, The Beaumont Enterprise/AP.

On May 7, 2008, a 20-foot-wide sinkhole in Daisetta, Texas, began swallowing everything in its path and had expanded to 900 feet by the next day with a depth of 260 feet. The former oil town sits on the Hull Salt Dome, a four-mile-in-diameter geologic formation of compacted salt, and geologists speculate that years of storing saltwater waste — a byproduct of oil production — caused the massive pit.

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Schmalkalden, Germany

Jens Meyer/AP.

A giant landslide under a residential street takes a car with it and leaves another car hanging over the edge in Schmalkalden, central Germany, on Nov. 1, 2010. (This sinkhole is more of the surprise variety, with not a lot of background to share at this point, but we thought you might find it noteworthy.)