Cave diving isunderwater diving in water-filledcaves. The equipment used varies depending on the circumstances, and ranges frombreath hold tosurface supplied, but almost all cave diving is done usingscuba equipment, often in specialised configurations with redundancies such assidemount or backmounted twinset. Recreational cave diving is generally considered to be a type oftechnical diving due to the lack of afree surface during large parts of the dive, and often involves planneddecompression stops. A distinction is made by recreational diver training agencies between cave diving and cavern diving, where cavern diving is deemed to be diving in those parts of a cave where the exit toopen water can be seen by natural light. An arbitrary distance limit to the open water surface may also be specified.[1] Despite the risks, water-filled caves attract scuba divers,cavers, andspeleologists due to their often unexplored nature, and presentdivers with a technical diving challenge.
Cave diving venues can be found on all continents exceptAntarctica, where the average temperature is too low for water to remain liquid in caves.
There are few flooded caves inAfrica which are known and accessible. There are several inSouth Africa, a few in Namibia and Zimbabwe, and some large caves recently discovered inMadagascar.
There are a large number of flooded caves in the limestone regions and other regions of Asia, particularly in the karst regions of China and Southeast Asia. Some are accessible for recreational cave diving, but most have probably not yet been found or explored.
Australia has many spectacular water filled caves andsinkholes, many of them in the Mount Gambier region of South Australia.
Europe has a large number of flooded caves, particularly in the karst regions.
North America has many cave diving venues, particularly in Florida, US, and the Yucatan Peninsula of Mexico.
South America has some cave diving venues in Brazil.
There are few flooded caves in Africa which are known and accessible.
There are a large number of flooded caves in the limestone regions and other regions of Asia. Some are accessible for recreational cave diving, but most have probably not yet been found or explored.
The Karst landforms in China's Guangxi, Yunnan, Guizhou and other provinces are extremely conducive to the development of caves, and thus give rise to rich groundwater features. 10 underground rivers with a length of more than 80 kilometers have been discovered, with hundreds of caves, skylights, "Feilai Lake" and other landscapes. However, in Guangxi and other places, the caves available for diving also have the characteristics of large water flow, fast speed, deep caverns, complex structure, and harsher cavern environment.
In recent years, Nanning Red Army hole, the sun and the moon hole, Liuzhou Fairy Cave, a series of cave systems attracts a large number of cave diving enthusiasts.[3]
Pawod Underwater Cave inMactan Island, off the island of Cebu in the CentralPhilippines was discovered in 2001 by Dr. Alfonso Amores. The discovery opened cave diving for the locals who erstwhile could not afford the expensive course in Florida. In 2012, Jake Miranda, Dr. Alfonso Amores and Bernil H. Gastardo founded the Filipino Cave Divers (FCD).[4] Exploration opened the freshwater caves of Casili,Balamban in Cebu Island and Enchanted River Underwater Cave inHinatuan, Surigao del Sur in the big southern island ofMindanao. Several more caves in Mindanao have since been discovered and explored – Bababu Lake (Dinagat Island), Pamutuanan Cave (Lianga, Surigao del Sur) and Campomento Cave (Lanuza, Surigao del Sur).[citation needed]
There are a number of freshwater filled cave sites located near and withinKupang, the principal city inWest Timor and the provincial capital ofEast Nusa Tenggara. At least 2 sites have been described:Gua Oehani (translates as the Oehani Cave) andGua Kristal (translates as the Crystal Cave).[5][6]
As of 1999, there was no requirement to hold cave diving certification to dive either of these sites. However, competence equivalent toCDAA Advanced Cave and Cave/Advanced Cave respectively appears to be appropriate for these sites.[6]
Australia has many spectacular water filled caves andsinkholes, but unlike the UK, most Australian cave divers come from a general ocean-diving background.
The "air-clear" water conditions experienced in the sinkholes and caves found in the Lower South East (now called theLimestone Coast) ofSouth Australia (SA) has attracted many visiting divers with the first cave and sinkhole dives taking place in the very late 1950s.[7] Until the mid-1980s divers generally used singlediving cylinders and homemade torches, andreels, resulting in most of their explorations being limited. Mixed-gas andrebreather technologies can now be used in many sites. The area is usually known within the cave diving community as theMount Gambier region.[citation needed]
A series of incidents between 1969 and 1974 in the former Lower South East of SA in which 11 divers died (including a triple and a quadruple fatality) in the following four karst features –Kilsbys Hole,Piccaninnie Ponds,Death Cave (also known asAlleyns Cave) andThe Shaft – created much public comment and led to the formation of theCave Divers Association of Australia Inc. (CDAA) in September 1973.[8] The introduction of a testing program by the CDAA in 1974, which involved the assessment of prospective cave divers' cave diving ability led to a reduced fatality rate. In 1989, this testing system was replaced by a training system which consists of three levels of qualification –Deep Cavern,Cave andAdvanced Cave.[9] Five further deaths have occurred since 1974; two died atPiccaninnie Ponds in 1984, one person died atKilsbys Hole in 2010, and two people died in separate incidents atTank Cave in 2011 including noted cave diverAgnes Milowka.[10][11][12][13]
During the 1980s, theNullarbor Plain was recognized as a major cave-diving area, with one cave,Cocklebiddy, being explored for more than 6 kilometres, involving the use of large sleds to which were attached numerous diving cylinders and other paraphernalia, and which were then laboriously pushed through the cave by the divers. In more recent years divers have been utilizing compactdiver-towing powered scooters, but the dive is still technically extremely challenging.[citation needed]
A number of other very significant caves have also been discovered during the past 20 years or so; the 10+ (Lineal) kilometre longTank Cave nearMillicent in theLimestone Coast, other very large features on the Nullarbor and the adjacent Roe Plain as well as a number of specific sites elsewhere, and nowadays the cave diving community utilizes many techniques, equipment and standards common internationally.[citation needed]
TheCave Divers Association of Australia is the major cave diving organisation in Australia and is responsible for the administration of cave diving at many sites. All cave diving in theLimestone Coast as well as at some New South Wales sites and the Nullarbor requires divers to be members of the CDAA, whether in the capacity of a visitor or a trained and assessed member. A number of other organisations participate in cave diving activities within Australia. TheAustralian Speleological Federation Cave Diving Group which was formed in 2005 coordinates projects focused on exploration and mapping at sites throughout Australia.[14] The following diving training organisations offer courses in various aspects of cave diving via instructors either resident in Australia or visiting from overseas –Global Underwater Explorers,International Association of Nitrox and Technical Divers andTechnical Diving International.[citation needed]
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Una National Park, in theBihac municipality, encompasses the valley of theUna River and is a hotspot forspeleological research expeditions. Thanks to the area's position between the end of two large karst systems:Plješivica andGrmeč, the river abounds with shallow water sources and a significant number of underwater caves.[15] So far, 10 large caves have been registered, only five of which have been partially examined.[16] Divers who have explored Klokot Spring have managed to reach a depth of 104.5 metres (343 feet; 57 fathoms), though the bottom of the spring has yet to be touched. Another cave has been explored to the length of 150 m (490 ft),[citation needed][clarification needed] and is said to be an ideal destination for cave divers in training.[citation needed][clarification needed]
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Hranice Abyss, or Hranická Propast, is the world's deepest known underwater cavity. It beat the previous record holder,Pozzo del Merro in Italy, by 12 m (39 ft).[17] Polish explorerKrzysztof Starnawski, who has explored the upper parts of the flooded fissure for decades, has determined the depth to be at least 404 m (1,325 ft) . As of 2017, divers have yet to reach the bottom of the cave.[18]
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Molnár János Cave is an active thermal water cave located on the western banks of theDanube river. Belonging to theBuda Hills karst system, which is home to many ofBudapest's famed hot springs, the temperature of the water sits between 20 and 28 °C (68 and 82 °F) year-round.[19] Whilst the first underwater explorations began in the 1950s, the cave wasn't successfully charted until the 70s and 80s when a group of divers mapped out more than 400 m (1,300 ft) of the cave system.[20] The cave, which contains a labyrinth passages, currently stretches to over 6 km (4 mi; 20,000 ft) though there are many more untouched sections to explore.
After the death of a diver in 2011, the Hungarian government imposed strict rules for diving. To dive at Molnár János, divers must have at least an intro-to-cave-diving certification or they cannot dive in the tunnels; they must have dive insurance that covers cave diving; and they must have air supplied in the form of double tanks, stages or a rebreather. In addition, each dive is accompanied by a guide, to minimize the risk of a wrong turn.[21]
Silfra is a fissure between the North American and Eurasian tectonic plates inThingvellir National Park. It is the only place in the world where you can dive or snorkel directly in a crack between two tectonic plates.[22] The tunnel from the entrance of Silfra to the cave is commonly known as ‘The Tunnel’, due to the strong current that ‘flushes’ divers attempting to swim through. This tunnel is rarely dived due to the dangerous head-first vertical dive needed to pass through. The deepest part of the cave is at least 63 m (207 ft) deep, and has only been dived by a few people because of the narrow and unstable passages.[23]
Pollatoomary in the Partry Mountains near Killavally, Westport, County Mayo, is the deepest explored underwater cave in Ireland.[24][25]
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In the north west ofSardinia, close toPorto Conte bay,Alghero territory, there are more than 300 caves above and below water, with about 30 large, and many smaller, underwater sea caves in the limestone cliffs ofCapo Caccia andPunta Giglio. TheNereo Cave is the most important and is considered the largest in the Mediterranean Sea. On the east side of Sardinia there are many underwater cave systems starting from theGennargentu Mountains, with underwater rivers. There is a fresh water cave of more than 110 m (360 ft) depth in this area.[citation needed]
Cala Gonone is considered the best departure point for cave diving in Sardinia's largest cave systems which are usually reached by sea.Bue Marino is the longest known. Some other known caves in the area are Cala Luna (Moon beach), Bel Torrente (with a great halocline), Grotta del Fico, Utopia, Euphoria, amongst others.[citation needed] The caves are to be dived by experienced and trained cave divers with required certification levels only. Some known dive centers catering to this technical cave level dives includeBase 1 that follows theGUE standards for diving andProtec
Jordbrugrotta (also known as Pluragrotta) is acave inRana Municipality.[26] It is the deepest cave inNorthern Europe.[26]
Cave divers occasionally visit Jordbrugrotta which is the most dived cave inScandinavia. Most of the other approximately 200 caves in Rana are not suitable for diving, and formation of caves has been limited due most of the rock being granite. Another diveable cave nearby isLitjåga. Damming ofKallvatnet made diving in Jordbrugrotta possible. There have been multiple cases of fatalities and injuries among visiting cave divers, but the accident rate is not out of proportion with the number of divers. The cave's passages were formed by the riverPlura's flow through porouslimestone.[27] Rock formations includemarble.[28][26] Visibility in the cave is good.[29]
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UK requirements are generally that all people wishing to take up cave diving must be competent cavers before they start cave diving. This is primarily because most British cave dives are at the far end of dry caves. There are individuals that begin cave diving directly from therecreational diving, but they represent a minority in the UK, and represent only a few percent of theCave Diving Group (CDG).[citation needed]
The caves and caverns ofGrand Bahama contain an immense underwater cavern with a vast floodedlabyrinth of caverns, caves and submerged tunnels that honeycomb the entire island of Grand Bahama and the surrounding sea bed. The inland caves are not abundant with life, but do contain creatures living in the caves other than the migratinggray snappers. Residents of these caves include a type of blind cave fish andremipedia that don't pose any threat to cave divers.[citation needed]
The caves in theBahamas were formed during the lastice age. With much of the Earth's water held in the form of glacial ice, the sea level fell hundreds of feet, leaving most of the Bahama banks, which are now covered in water, high and dry. Rain falling on the most porous limestone slowly filtered down to sea level forming a lens where it contacted the denser salt water of the ocean permeating the spongy limestone. The water at the interface was acidic enough to dissolve away the limestone and form the caves. Then, as more ice formed and the sea level dropped even further, the caves became dry and rainwater dripping through the ceiling over thousands of years created the incredible crystal forests of stalagmites which now decorate the caves. Finally, when the ice melted and the sea level rose, the caves were reclaimed by the sea.[citation needed]
There is a growing number of known water filled caves in the Dominican Republic, spread all over the island. Regions with underwater caves include Santo Domingo, Pedernales, Cabrera, Bayahibe and others.
Active exploration is being conducted by the Dominican Republic Speleological Society which is working together with local institutions as well as international scientists to further explore all the cave systems possibilities and focusing in the preservation.[citation needed]
The longest known cave in the island isEl Toro which is about 1,800 m (6,000 ft) in length.[citation needed]
The best known caves in the island areCueva Taina,El Tildo,El Chicho andEl Dudu, which have easy access to the water and with a good level of safety outside of the water as they are in private properties or national parks.[citation needed]
Cave diving is playing a very important role in science in the DR,[citation needed] in the last 3 years the DRSS team together with international scientists and "Museo del Hombre Dominicano"[citation needed] has found a new species of cave bacteria, a number of new and extinct bat species, the first evidence of extinct crocodiles in the DR, fossil snakes, birds, sloths and remains of long extinct monkeys and other ancient cave life.[citation needed]DRSS has cataloged over 120 new springs all over the island in which many have caverns and cave systems attached.[citation needed]
Safety concerns in Dominican Republic
An important safety issue on the island is untrained cave diving, principally led by unprofessional dive stores and guides risking their customers' lives.[citation needed] Unprofessional and unsafe practices of dive guides may be reported to the relevant dive agency and to the Dominican Republic Speleological Society.[33]
Yucatán Peninsula
While there is great potential for cave diving in the continental karst throughout Mexico, the majority of cave diving in Mexico occurs in the Yucatán Peninsula. While there are thousands of deep pit cenotes throughout the Yucatán Peninsula including in the states ofYucatán andCampeche, the extensive sub-horizontal flooded cave networks for which the peninsula is known are essentially limited to a 10 km wide strip of the Caribbean coastline in the state ofQuintana Roo extending south fromCancún to theTulum Municipality and theSian Ka'an Biosphere Reserve, although some short segments of underwater cave have been explored on the north-west coast (Yucatán State).[citation needed]
In the Yucatán Peninsula, any surface opening where groundwater can be reached is calledcenote, which is a Spanish form of the Maya wordd'zonot. The cave systems formed as normal caves underwater, but upper sections drained becoming air filled during past low sea levels. During this vadose, or air filled state, abundantspeleothem deposits formed. The caves and the vadose speleothem were reflooded and became hydraulically reactivated as rising sea levels also raised the water table. These caves are therefore polygenetic, having experienced more than one cycle of formation below the water table. Polygenetic coastal cave systems with underwater speleothem are globally common, with notable examples being on the Balearic Islands (Mallorca,Menorca) of Spain, the islands of the Bahamas, Bermuda, Cuba, and many more.[citation needed]
The underwater speleothems in the Yucatán Peninsula are fragile. If a diver accidentally breaks a formation, it will not reform as long as the cave is underwater so active cave conservation diving techniques are necessary.[clarification needed] The Quintana Roo caves are extremely complex withanastomotic interconnected passages. When diving through the caves, they appear to have many offshoots and junctions, requiring careful navigation with permanent tees or the implementation of jumps in the guideline.[citation needed]
The beginning of the 1980s brought the first cave divers from the U.S. to the Yucatán Peninsula, Quintana Roo to explore cenotes such asCarwash,Naharon andMaya Blue, and to central Mexico where resurgence rivers such asRio Mante, and sinkholes such asZacaton were documented.[34]
In the Yucatán, the 1980s ended with the discoveries of theDos Ojos andNohoch Nah Chich cave systems which led into a long competition of which exploration team had the longest recorded underwater cave system in the world at the time.[citation needed]
The beginning of the 1990s led into the discovery of underwater caves such asAereolito on the island ofCozumel, ultimately leading to the 5th biggest underwater cave in the world.[citation needed]
By the mid-1990s a push into the central Yucatán Peninsula discovered a large number of deep sinkholes, or pit cenotes, such asSabak Ha andUtzil, and deep caves such asChacdzinikche,Dzibilchaltun andKankirixche that have since been explored and mapped. These deep caves of the central Yucatán remain largely unexplored due to the number of cenotes in the State of Yucatán, and the depths, which require technical diving techniques or rebreathers. At the end of the last millennium closed circuit rebreathers were used to explore these caves.[citation needed]
By the end of the 1990s,The Pit in theDos Ojos cave system located 5.8 km from the Caribbean coast had been discovered, and by 2008 it had been dived to 119 m deep. At that time, technical diving and rebreather equipment and techniques became commonplace.[citation needed]
By the turn of the millennium the longest underwater cave system at that time,Ox Bel Ha was established by cave diving explorers whose combined efforts and information helped join segments of previously explored caves. The use of hand held GPS technology and aerial and satellite images for reconnaissance during exploration became common. New technology such as improved rebreathers and diver propulsion vehicles (DPVs) became available and were utilized for longer penetration dives. In January 2013,Ox Bel Ha included 242 km of underwater passage (seeQRSS for current statistics).[citation needed]
Active exploration continues in the new millennium. Most cave diving exploration is now conducted on the basis of "mini projects" lasting 1–7 days, and occurring many times a year, and these may include daily commutes from home to jungle dive base camps located within 1 hour from road access.[citation needed]
Starting in 2006 a number of large previously explored and mapped cave systems have been shown to be connected using sidemount and often no-mount cave diving techniques to pass through tight cave passages, indicating the largest known connected underwater cave system on the planet,Sac Actun, which is 220 km long (seeQRSS for current statistics).[citation needed]
Many cave maps have been published by the Quintana Roo Speleological Survey (QRSS).[citation needed]
Central and Northern Florida
The largest and most active cave diving community in the United States is in north-centralFlorida. The North FloridanAquifer expels groundwater through numerous first-magnitudesprings, each providing an entrance to the aquifer's labyrinthine cave system. These high-flow springs have resulted in Florida cave divers developing special techniques for exploring them, since some have such strong currents that it is impossible to swim against them.[citation needed]
The longest known underwater cave system in the United States, TheLeon Sinks cave system, near Tallahassee, Florida, has multiple interconnected sinks and springs spanning two counties (Leon & Wakulla).[35] One main resurgence of the system,Wakulla Springs, is explored exclusively by a very successful and pioneering project called theWoodville Karst Plain Project (WKPP), although other individuals and groups like the US Deep Cave Diving Team, have explored portions ofWakulla Springs in the past.[citation needed]
One deep underwater cave in the United States isWeeki Wachee Spring. Due to its strong outflow, divers have had limited success penetrating this first magnitude spring until 2007, when drought conditions eased the out-flowing water allowing team divers fromKarst Underwater Research to penetrate to depths of 120 m (400 ft)[36]
The Florida caves are formed from geologically younglimestone with moderate porosity. The absence of speleothem decorations which can only form in air filled caves, indicates that the flooded Florida caves have a single genetic phase origin, having remained water filled even during past low sea levels. In plan form, the caves are relatively linear with a limited number of side passages allowing for most of the guidelines to be simple paths with few permanent tees. It is common practice for cave divers in Florida to joint a main line with a secondary line using a jump reel when exploring side passages, in order to maintain a continuous guideline to the surface.[citation needed]
Texas
The current deepest known underwater cave in the United States as of 2013 is Phantom Springs Cave located in west Texas. Phantom Springs has been explored down to 141 m (462 ft) in water filled cave passages.[37]
In Brazil there is cavern diving inChapada da Diamantina, inBahia state;Bonito, inMato Grosso do Sul state; andMariana, where there is also cave diving (visitingMina da Passagem), inMinas Gerais state. For cave diving in Mariana a cave diver certification will be required.[citation needed]
