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Sinkholes have captured much attention in recent times, serving as stark reminders of nature's power to quickly reclaim its creations. Found all over the globe, these natural phenomena come in various forms. As an explorer, you’ll encounter sinkholes with unique features, such as hidden water sources or lush forests, while others may simply be large basins filled with earth. While awe-inspiring, they can also be dangerous and cause substantial destruction when they occur in populated areas.
Sinkholes are as striking as they are hazardous, with captivating blue holes, brilliant swimming spots, vast underground caverns, and sudden drops. Join us as we take a look at ten of the most famous sinkholes worldwide.
10. Qattara Depression, Egypt
Located in northwestern Egypt, particularly in the Matruh Governorate, the Qattara Depression is a part of Egypt's Western Desert. Beneath the depression lies a mix of salt pans, dunes, and salt marshes. The formation of the Qattara Depression resulted from the combination of wind erosion and salt weathering.
To the west of the depression, about 12 miles (20 kilometers) away, lie the oases of Siwa in Egypt and Jaghbub in Libya, situated in smaller but similar depressions.
9. Blue Hole of Dahab, Egypt
The Dahab Blue Hole, one of Sinai’s most famous landmarks and a must-visit destination in Egypt, is located on the Red Sea coast of the Sinai Peninsula, just north of Dahab. Divers and tourists from around the world flock here to experience its underwater wonders.
The first part of the Blue Hole is a 20-foot (6-meter) deep section known as 'The Saddle.' This leads to a tunnel, 'The Arch,' which spans 85 feet (26 meters) and has a ceiling that reaches 180 feet (55 meters). The tunnel's base extends into the sea, reaching a depth of about 394 feet (120 meters). The seaward side of the hole can reach depths between 3,280 and 9,650 feet (1,000 to 3,000 meters).
Famed for its appeal to freedivers due to its easy access from the shore and lack of strong currents, the Blue Hole holds the grim title of having the most diving fatalities in the world, with an estimated 130 to 200 divers losing their lives in recent years. While the cause of its dangerous reputation remains a mystery, it's clear that this location is not suited for novice divers.
8. Macocha Gorge, Czech Republic
The Moravian Karst cave system in the Czech Republic features a remarkable sinkhole known as the Macocha Abyss, also referred to as the Macocha Gorge. This sinkhole is the deepest of its kind in Central Europe, plunging 454 feet (138.5 meters). It's a favorite destination for tourists, especially cavers and skilled divers seeking adventure.
The area around Macocha, with its lush greenery, exudes a mystical aura. Much like Prague’s notorious Nuselsk Bridge, this location is infamous for being the site where many individuals have tragically ended their lives over the last century.
However, the natural beauty of the region offers an uplifting atmosphere. The abundant foliage is a soothing sight, acting almost like a tranquilizer. Both the upper and lower bridges offer stunning views of the abyss. The lower bridge, 300 feet (92 meters) above the chasm’s bottom, provides an unobstructed view, while the upper bridge, perched at a height of 453 feet (138 meters), offers a breathtaking perspective from above.
7. Cennet-Cehennem, Turkey
In Turkey’s Mersin Province, located in the Taurus Mountains, there are two immense sinkholes called Cennet (Heaven) and Cehennem (Hell). Their massive size and unique features have made them increasingly popular as tourist attractions.
The vast depression known as Cennet ökügü (Heaven) stretches 820 feet (250 meters) in length, 360 feet (110 meters) in width, and varies in depth between 196 and 230 feet (60 to 70 meters). Accessing it requires a climb up a 426-step limestone staircase, making the journey quite demanding. The floor of the pit is largely covered with trees and bird nests. A refreshing breeze marks the entrance to a cave, where a fifth-century chapel dedicated to the Virgin Mary resides. The church, which faces east and west, has a rectangular shape with six arched windows on its longer sides. A four-line inscription on the western side’s door reads that a pious man named Paulus constructed the church in honor of the Virgin Mary.
A vaulted structure surrounds the apse and the monks’ quarters on either side. The apse is decorated with frescoes of Christ and his apostles. A trail leads to a sump where a cold underground stream emerges from the cave behind the church. At the far end of the site stands an ancient Zeus Temple from the Hellenistic period. The north wall of the temple bears the names of 130 priests who served during the Hellenistic and Roman eras. The Doric-style temple was later transformed into a church during the Christian era.
Located about 245 feet (75 meters) to the northeast of Cennet, Cehennem (Hell) features a nearly circular daylight shaft. The shaft measures 197 feet (60 meters) across and plunges to a depth of 394 feet (120 meters). Although its circumference is smaller, its greater depth and eerie appearance have caused locals to associate it with “hell.” The chapel at Cennet likely contributed to the naming of the other pit as “heaven.” Visitors can descend into this sinkhole via a steel ladder, though this is not recommended for ordinary tourists due to the inherent risks.
6. Devil’s Sinkhole, Texas
The Devil’s Sinkhole, located in Texas, is one of the state's most renowned caverns and a celebrated natural wonder in the United States. This immense cavern is a shaft with a diameter ranging from 65 to 98 feet (20 to 30 meters), plunging to a depth of 138 feet (42 meters). Its expansive floor has a diameter exceeding 328 feet (100 meters), making it the largest and third-deepest single-chamber cavern in Texas. Designated as a National Landmark since 1985, the sinkhole is part of a vast network of caverns beneath the Edwards Plateau, stretching across central and western Texas. The sinkhole was created by the collapse of an underground void.
During the summer, millions of Mexican Free-Tailed Bats make the sinkhole their home. At dusk, visitors can begin to see a few bats emerging, and as the night falls, they are soon followed by a swirling mass of millions of bats soaring into the sky.
5. El Zacaton Sinkhole, Mexico
El Zacaton is the world’s deepest known water-filled sinkhole, plunging to an astonishing depth of 1,112 feet (339 meters). While the Pozzo del Merro is deeper, with an estimated depth of 1,286 feet (392 meters), its classification remains uncertain, as it may be a nearly vertical cave rather than a true sinkhole. Tragically, at least one diver has lost their life in attempts to reach the bottom, a feat that has yet to be accomplished.
The most striking feature of the karst landscape surrounding El Zacaton is the sinkhole itself. This region is home to more than 20 distinct geological phenomena, including other sinkholes, hot springs heated by volcanic activity, caves, and travertine formations.
Among five unusual sinkholes that are in close proximity but not physically connected, El Zacaton stands out as the deepest. Its name is derived from Zacate grass islands, which float and shift according to the wind's direction. Due to its impressive depth, El Zacaton has become a sought-after location for divers, with both male and female divers setting world records here.
4. Cave of Swallows, Mexico
The Cave of Swallows is home to a wide array of regional wildlife and is considered one of the six most remarkable and bottomless underground caves. As a result of minimal human disturbance, it is protected within the San Luis Potosi Natural Area. The cave features a vertical drop of 1,220 feet (372 meters)—or 1,904 feet (580 meters) from its highest edge—leading down to the cave floor. This type of cave is known as a pit cave, essentially a massive 160- to 205-foot (49- to 62-meter) opening in the forest floor. If placed upright, structures like the Chrysler Building, the Eiffel Tower, or the Statue of Liberty could all fit inside.
The Cave of Swallows is so tall that it's a popular spot for BASE jumpers (Buildings, Antennas, Spans, and Earth) who take the plunge from the edge, experiencing free-fall for a few seconds before deploying their parachutes. Extreme sports enthusiasts flock to this location.
3. Xiaoxhai Tiankeng, China
Xiaozhai Tiankeng, the largest sinkhole in the world, stretches over 2,000 feet in length, 1,762 feet in width, and about 2,200 feet in depth (610 meters long, 537 meters wide, and 671 meters deep). Also called the Xiaozhai Heavenly Pit, this remarkable karst sinkhole is located in the Shaanxi Cluster, in China's Shaanxi Province. Its unique structure is formed as a double-nested doline, consisting of two distinct bowls. The deeper of the two bowls reaches 1,122 feet (342 meters), while the upper bowl is around 1,050 feet (320 meters) deep. The two sections are separated by a sloping ridge.
Although locals had known about the Xiaozhai Tiankeng for a long time, it wasn't until 1994 that British explorers brought it to the attention of the global community. While investigating its underground cave system, the explorers encountered numerous unsuccessful attempts to explore the sinkhole, facing difficulties navigating its turbulent waters. As a result, the sinkhole's geological makeup remains largely unexplored. The sinkhole's formation is closely tied to an underground river that still flows through it, positioned above the Dinfeng Cave.
2. Crveno Jezero, also known as the Red Lake, located in Croatia.
The karst formation of Crveno Jezero is internationally renowned for its impressive size and distinctive features. During the 1950s, several hydrological measurements were taken from the lake's surface, including depth readings at 39 different locations.
The Red Lake, less than a mile (one kilometer) west of Imotski, is the largest in the region, encompassing both visible and hidden areas. It consists of 18 depressions, large and small, that are either dry or filled with water. The lake gets its name from the red rocks that adorn cliffs towering over 820 feet (250 meters) above the ground.
1. The Great Blue Hole, Belize
The Great Blue Hole, one of the most remarkable natural wonders, lies just off the coast of Belize on Central America's eastern seaboard. It is located near the Center of Lighthouse Reef, an atoll roughly 62 miles (100 kilometers) from Belize City, which sits on the mainland.
This immense underwater sinkhole, known as the Great Blue Hole, plunges to a depth of 410 feet (125 meters) and spans over 984 feet (300 meters) across. Situated on the Lighthouse Reef Atoll—one of Belize's three atolls—the hole is part of the Belize Barrier Reef Reserve System, a UNESCO World Heritage Site. It forms a near-perfect circle in the center of the Lighthouse Reef coral system.
The Great Blue Hole enjoys a dedicated global following, with many Belizeans fervently advocating for its inclusion as one of the seven natural wonders of the world. In 2012, The Discovery Channel ranked it as the top destination on Earth.
