A sinkhole is a depression or hole in the ground caused by some form of collapse of the surface layer. The term is sometimes used to refer to doline, enclosed depressions that are locally also known as vrtače and shakeholes, and to openings where surface water enters into underground passages known as ponor, swallow hole or swallet. A cenote is a type of sinkhole that exposes groundwater underneath. A sink or stream sink are more general terms for sites that drain surface water, possibly by infiltration into sediment or crumbled rock.
Cave diving is underwater diving in water-filled caves. It may be done as an extreme sport, a way of exploring flooded caves for scientific investigation, or for the search for and recovery of divers lost as a result of one of these activities. The equipment used varies depending on the circumstances, and ranges from breath hold to surface supplied, but almost all cave diving is done using scuba equipment, often in specialised configurations with redundancies such as sidemount or backmounted twinset. Recreational cave diving is generally considered to be a type of technical diving due to the lack of a free surface during large parts of the dive, and often involves planned decompression stops.
Sheck Exley was an American cave diver. He is widely regarded as one of the pioneers of cave diving, and he wrote two major books on the subject: Basic Cave Diving: A Blueprint for Survival and Caverns Measureless to Man. On February 6, 1974, Exley became the first chairman of the Cave Diving Section of the National Speleological Society. During his career, he established many of the basic safety procedures used in cave and overhead diving today. Exley was also a pioneer of extreme deep scuba diving.
A cenote is a natural pit, or sinkhole, resulting from the collapse of limestone bedrock that exposes groundwater. The regional term is specifically associated with the Yucatán Peninsula of Mexico, where cenotes were commonly used for water supplies by the ancient Maya, and occasionally for sacrificial offerings. The term derives from a word used by the lowland Yucatec Maya—tsʼonot—to refer to any location with accessible groundwater.
The Blue Lake is a large, monomictic, crater lake located in a dormant volcanic maar associated with the Mount Gambier maar complex. The lake is situated near Mount Gambier in the Limestone Coast region of South Australia, and is one of four crater lakes on Mount Gambier maar. Of the four lakes, only two remain, as the other two have dried up over the past 30 to 40 years as the water table has dropped.
The Woodville Karst Plain Project or WKPP, is a project and organization that maps the underwater cave systems underlying the Woodville Karst Plain. This plain is a 450-square-mile (1,200 km2) area that runs from Tallahassee, Florida, U.S. to the Gulf of Mexico and includes numerous first magnitude springs, including Wakulla Springs, and the Leon Sinks Cave System, the longest underwater cave in the United States. The project grew out of a cave diving research and exploration group established in 1985 and incorporated in 1990.
Wes Skiles Peacock Springs State Park is a 733-acre (297 ha) Florida State Park located on Peacock Springs Road, two miles (3 km) east of Luraville and on State Road 51, 16 miles (26 km) southwest of Live Oak, Florida. Activities include picnicking, swimming and diving, and wildlife viewing. Among the wildlife of the park are deer, bobcats, raccoon, squirrels, beaver and otters, as well as turkey, blue heron and barred owls. The park name commemorates the work of diver and explorer Wes Skiles. Prior to 2010 the park was known as Peacock Springs State Park. Amenities include a nature trail, six sinkholes, and Peacock and Bonnet Springs, with miles of underwater caves popular with cave divers. The two springs are tributaries of the Suwannee River. The park is open from 8:00 am till sundown year round.
Dos Ojos is part of a flooded cave system located north of Tulum, on the Caribbean coast of the Yucatán Peninsula, in the state of Quintana Roo, Mexico. The exploration of Dos Ojos began in 1987 and still continues. The surveyed extent of the cave system is 82 kilometers (51 mi) and there are 28 known sinkhole entrances, which are locally called cenotes. In January 2018, a connection was found between Sistema Dos Ojos and Sistema Sac Actun. The smaller Dos Ojos became a part of Sac Actun, making the Sistema Sac Actun the longest known underwater cave system in the world.
The Warm Mineral Springs is a water-filled sinkhole located in North Port, Florida, a mile north of U.S. 41. The primary water supply is a spring vent deep beneath the pool's water surface. Warm Mineral Springs is the only warm water mineral spring in the State of Florida. It is an important geological and archaeological site containing Native American remnants. It functioned as a small natural spa since the 1960s. People travel from all over the world to soak in the mineral-rich waters. It has been reputed to be the fountain of youth sought by Ponce de Leon with healing powers. It was added to the U.S. National Register of Historic Places on November 28, 1977. The springs re-opened for swimming only in 2014.
The District Council of Grant is a local government area located in the Limestone Coast region of South Australia, and is the southernmost council in the state.
Sistema Sac Actun is an underwater cave system situated along the Caribbean coast of the Yucatán Peninsula with passages to the north and west of the city of Tulum. Discovery of a connection to the Sistema Dos Ojos in 2008 made it the longest known underwater cave system.
Piccaninnie Ponds Conservation Park, formerly the Piccaninnie Ponds National Park, is a protected area of 862 hectares located in southeastern South Australia near Mount Gambier.
Ewens Ponds is a series of three water-filled limestone sinkholes in the Australian state of South Australia located in the gazetted locality of Eight Mile Creek, on the watercourse of Eight Mile Creek about 25 kilometres south of Mount Gambier and 8.4 kilometres east of Port Macdonnell. The ponds are popular with recreational divers due to underwater visibility of up to 80 metres. It has a large fish population including the endangered golden pygmy perch. Ewens Ponds has been part of the Ewens Ponds Conservation Park since 1976.
The Nambung River is a river in the Wheatbelt region of Western Australia, 170 kilometres (106 mi) north of Perth. The river drains an area between the towns of Cervantes and Badgingarra. In its lower reaches the Nambung River forms a chain of waterholes in the Nambung Wetlands where it disappears underground into a limestone karst system 5.5 kilometres (3 mi) from the Indian Ocean.
The Cave Divers Association of Australia (CDAA) is a cave diving organisation which was formed in September 1973 to represent the interests of recreational scuba divers who dive in water‐filled caves and sinkholes principally in the Lower South East of South Australia (SA) and secondly in other parts of Australia. Its formation occurred after a series of diving fatalities in waterfilled caves and sinkholes in the Mount Gambier region between 1969 and 1973 and in parallel to a South Australian Government inquiry into these deaths. The CDAA's major achievement has been the dramatic reduction of fatalities via the introduction of a site rating scheme and an associated testing system which was brought in during the mid-1970s. While its major area of operation is in the Limestone Coast region of SA, it administers and supports cave diving activity in other parts of Australia including the Nullarbor Plain and Wellington, New South Wales.
Agnes Milowka was an Australian technical diver, underwater photographer, author, maritime archaeologist and cave explorer. She gained international recognition for penetrating deeper than previous explorers into cave systems across Australia and Florida, and as a public speaker and author on the subjects of diving and maritime archaeology. She died aged 29 while diving in a confined space.
Little Blue Lake is a water-filled doline in the Australian state of South Australia located in the state's south-east in the locality of Mount Schank about 20 kilometres (12 mi) south of the municipal seat of Mount Gambier. It is notable locally as a swimming hole and nationally as a cave diving site. It is managed by the District Council of Grant and has been developed as a recreational and tourism venue.
Engelbrecht Cave is a cave system in the Australian state of South Australia consisting of a sinkhole with two major passages located under the Mount Gambier urban area. It is owned by the local government area of City of Mount Gambier and has been developed as a tourism venue. Its dry extent is notable as a show cave while its water-filled extent is notable as two separate cave diving sites.
The Kilsby sinkhole is a sinkhole located near Mount Gambier in South Australia. Since the late 1960s, the naturally occurring karst sinkhole has been used for recreational diving as well as civilian and police diver training.
The 1973 Mount Gambier cave diving accident was a scuba diving incident in 1973 at a flooded sinkhole known as "The Shaft" near Mount Gambier in South Australia. The incident claimed the lives of four recreational scuba divers: siblings Stephen and Christine M. Millott, Gordon G. Roberts, and John H. Bockerman. The four divers explored beyond their own planned limits, without the use of a guideline, and subsequently became lost, eventually exhausting their breathing air and drowning. As of May 2015, they are the only known fatalities at the site. Four other divers from the same group survived.
