Heavy rains from tropical storm Agatha likely triggered the collapse of a huge sinkhole in Guatemala in June 2010 seen above a few days afterward.
Photographs by Daniel LeClair, Reuters
The Guatemala sinkhole fits into a broader use of the term, which refers to any sudden slump of the ground's surface. Instead of solid bedrock, much of Guatemala City rests atop a layer of loose, gravelly volcanic pumice that is hundreds of feet thick. And at least one geologist says leaking pipes—not nature—created the recent sinkhole. Typically, officials fill in sinkholes with large rocks and other debris. Over time, erosion by water and the drying effects of air will also cause the sides of a sinkhole to slope inward.
Sarisarinama Tepui Sinkhole, Venezuela
This awe inspiring sinkhole is on the tip-top of a high mountain peak. The Sarisariñama tepui is a 2,350-metre high mountain in the Jaua-Sarisariñama National Park at the far south-west of Bolívar State, Venezuela, near the border with Brazil. The most distinctive features of this tepui are its sinkholes, which were first brought to attention of modern scientists in 1961 by a pilot who saw them from the air, yet it was not until 1974 that the mountain summit was reached and the sinkholes could be investigated.
Given the pristine state of the area and the opportunity to learn more about the ecology and geology, this region is not accessible by the general public – it is restricted to scientific endeavors only.
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Bimmah Sinkhole, Oman
Geologists say this 40 meter wide, 20 meter deep water-hole was created when a limestone cavern collapsed, but the locals say a piece of the moon fell from the sky and made the hole. There is a park created in the area around the sinkhole, complete with change rooms so visitors can swim and get into the water if they want to.
Florida Sinkhole - Winter Park
The sinkhole in Winter Park, Florida opened up in 1981 underneath the city's public swimming pool.
Photograph from Selbypic/AP
Florida Sinkhole, Mulberry
This 185-foot-deep (56-meter-deep) sinkhole appeared in 1994 in Mulberry, Florida in a pile of waste material dumped by mining company IMC-Agrico. The company was mining rock to extract phosphate, a main ingredient in fertilizers and a chemical used to produce phosphoric acid, added to enhance the taste of soda and various food items.
Photograph from Selbypic/AP
After phosphate was extracted from the rocks, the gypsum-based waste product was dumped as a slurry. As layer after layer of the stuff dried, it formed cracks, like those that appear in dried mud. Water later made its way through the cracks and carried away subsurface material, setting the stage for a sinkhole.
Blue Hole Sinkhole, Belize
Sinkholes can happen anywhere water can erode a vertical channel that connects to a horizontal drain, a situation that allows a column of solid material to wash away. If the sinkhole is near the sea—or in the sea, as with the famous Blue Hole in Lighthouse Reef off the coast of Belize—seawater can quickly seep in after a collapse, forming a deep pool.
Photograph by David Doubilet, National Geographic
Oklahoma Sinkhol, Picher
Years of mining for zinc and lead has left Picher, Oklahoma, near the border with Kansas (see map), literally full of holes—including this sinkhole seen in 2008. Some mines were dug too close to the surface, and the roofs were unable to support the weight of earth on top, leading to collapses.
Photograph by Charlie Riedel, AP
Adventure kayaker Mick Coyne lowers himself down the wall of a sinkhole toward the headwaters of the Jokulsa, Iceland's second longest river. Though the river is fed by melt from a glacier, this 150-foot (45-meter), inverted funnel-shaped hole was blasted into being by rising steam from geothermal vents below.
Photograph by Robert Gregoire and Jean-Luc Cheron, National Geographic
Mexico Sinkhole, Ik-Kil Cenote
Swimmers float in the saphirre waters of the Ik-Kil cenote, near the Maya site of Chichén Itzá in Mexico's Yucatán Peninsula. Cenote means "natural well" in Spanish. Sinkholes occurring at sea level will fill up as high as the water table, creating the famous clear blue pools, used by the Maya royalty for both relaxation and ritual sacrifices.
Photograph by Emmanuel Lattes, Alamy
Portugal Sinkhole, Lisbon
A parked bus was the unfortunate "meal" of a sinkhole that opened up in the streets of Lisbon, Portugal, in 2003. In many cities, utility infrastructure such as sewer lines and fiber optic cables are buried in troughs filled with loose material, which can wash away over time. In some cases, a stretch of road can essentially become a concrete bridge over mostly empty space.
Photograph by Jose Manuel Ribeiro, Reuters
Neversink Pit, Alabama
Neversink Pit, a wet limestone sinkhole in Alabama seen above in 1998, is about 50 feet (15 meters) deep and houses a rare species of fern. The sinkhole was bought in the 1990s by a group of cavers to preserve it for future generations. Karst is the geologic term for landscapes formed mainly by the dissolving of limestone or dolomite bedrock. In the United States, karst underlies parts of Missouri, Arkansas, Kentucky, Tennessee, northern Alabama, Texas, and most of Florida (see a USGS karst map). Such areas are marked by sinking streams, subterranean drainage, large springs, caves—and, of course, sinkholes.
Photograph by George Steinmetz, National Geographic
Neversink Pit Video
Dean’s Blue Hole, Bahamas
One of the deepest blue holes at 663ft deep, Dean’s Blue hole widens to a 100m cavern at about 20m down. It is named after the family who own the land nearby and is a very popular diving spot.
The Vertical Blue 2008 free-diving competition was held here in April, when 25 national records and 5 world records were broken, and just the year before free-diver William Trubridge from New Zealand shattered the free-diving world record reaching lung-squishing depth of 84m, without the use of fins!