A cave or cavern is a natural void under the Earth's surface. Caves often form by the weathering of rock and often extend deep underground. Exogene caves are smaller openings that extend a relatively short distance underground. Caves which extend further underground than the opening is wide are called endogene caves.
Odesa is the third most populous city and municipality in Ukraine and a major seaport and transport hub located in the south-west of the country, on the northwestern shore of the Black Sea. The city is also the administrative centre of the Odesa Raion and Odesa Oblast, as well as a multiethnic cultural centre. As of January 2021, Odesa's population was approximately 1,010,537. On 25 January 2023, its historic city centre was declared a World Heritage Site and added to the List of World Heritage in Danger by the UNESCO World Heritage Committee in recognition of its multiculturality and 19th-century urban planning. The declaration was made in response to the bombing of Odesa during the Russian invasion of Ukraine, which has damaged or destroyed buildings across the city.
The Catacombs of Paris are underground ossuaries in Paris, France, which hold the remains of more than six million people. Built to consolidate Paris's ancient stone quarries, they extend south from the Barrière d'Enfer former city gate; the ossuary was created as part of the effort to eliminate the effects of the city's overflowing cemeteries. Preparation work began shortly after a 1774 series of basement wall collapses around the Holy Innocents' Cemetery added a sense of urgency to the cemetery-eliminating measure, and from 1788, nightly processions of covered wagons transferred remains from most of Paris's cemeteries to a mine shaft opened near the Rue de la Tombe-Issoire .
Catacombs are man-made underground passages primarily used for religious purposes, particularly for burial. Any chamber used as a burial place is considered a catacomb, although the word is most commonly associated with the Roman Empire.
An underground city is a series of linked subterranean spaces that may provide a defensive refuge; a place for living, working or shopping; a transit system; mausolea; wine or storage cellars; cisterns or drainage channels; or several of these. Underground cities may be currently active modern creations or they may be historic including ancient sites, some of which may be entirely or partially open to the public.
Coquina is a sedimentary rock that is composed either wholly or almost entirely of the transported, abraded, and mechanically sorted fragments of mollusks, trilobites, brachiopods, or other invertebrates. The term coquina comes from the Spanish word for "cockle" and "shellfish".
A dugout or dug-out, also known as a pit-house or earth lodge, is a shelter for humans or domesticated animals and livestock based on a hole or depression dug into the ground. Dugouts can be fully recessed into the earth, with a flat roof covered by ground, or dug into a hillside. They can also be semi-recessed, with a constructed wood or sod roof standing out. These structures are one of the most ancient types of human housing known to archaeologists, and the same methods have evolved into modern "earth shelter" technology.
The Wren's Nest is a geological Site of Special Scientific Interest in the Dudley Metropolitan Borough, north west of the town centre of Dudley, in the West Midlands of England. It is one of the most important geological locations in Britain. It is also a Local Nature Reserve, a national nature reserve (NNR) and Scheduled Ancient Monument. The site is home to a number of species of birds and locally rare flora, such as Scabiosa columbaria, milkwort and quaking grass. The caverns are also a nationally important hibernation site for seven different species of bat.
Treak Cliff Cavern is a show cave near Castleton in Derbyshire, England. It is part of the Castleton Site of Special Scientific Interest and one of only two sites where the ornamental mineral Blue John is still excavated. As part of an agreement with English Nature, the Blue John that can be seen in the show cave is not mined but it is extracted in small quantities from other areas of the cave and made into saleable items like bowls, jewellery, and ornaments.
Tunnel warfare is using tunnels and other underground cavities in war. It often includes the construction of underground facilities in order to attack or defend, and the use of existing natural caves and artificial underground facilities for military purposes. Tunnels can be used to undermine fortifications and slip into enemy territory for a surprise attack, while it can strengthen a defense by creating the possibility of ambush, counterattack and the ability to transfer troops from one portion of the battleground to another unseen and protected. Also, tunnels can serve as shelter from enemy attack.
Mine exploration is a hobby in which people visit abandoned mines, quarries, and sometimes operational mines. Enthusiasts usually engage in such activities for the purpose of exploration and documentation, sometimes through the use of surveying and photography. In this respect, mine exploration might be considered a type of amateur industrial archaeology. In many ways, however, it is closer to caving, with many participants actively interested in exploring both mines and caves. Mine exploration typically requires equipment such as helmets, head lamps, Wellington boots, and climbing gear.
Running beneath the Italian city of Naples and the surrounding area is an underground geothermal zone and several tunnels dug during the ages. This geothermal area is present generally from Mount Vesuvius beneath a wide area including Pompei, Herculaneum, and from the volcanic area of Campi Flegrei beneath Naples and over to Pozzuoli and the coastal Baia area. Mining and various infrastructure projects during several millennia have formed extensive caves and underground structures in the zone.
The mines of Paris comprise a number of abandoned, subterranean mines under Paris, France, connected together by galleries. Three main networks exist; the largest, known as the grand réseau sud, lies under the 5th, 6th, 14th and 15th arrondissements, a second under the 13th arrondissement, and a third under the 16th, though other minor networks are found under the 12th, 14th and 16th for instance. The commercial product was Lutetian limestone for use as a building material, as well as gypsum for use in "plaster of Paris".
The Milwr Tunnel is a mine drainage adit running some 10 miles from the hamlet of Cadole near Loggerheads, Denbighshire to Bagillt on the Dee Estuary in North Wales. It was originally built to drain the lead mines beneath Halkyn Mountain, which were plagued with flooding in their lower levels, but enabled the exploitation of new lodes and was variously used for the extraction of lead, zinc and limestone during its working history. It is part of a network of mines, lodes and natural cave systems – the Halkyn United Mines – that extends for up to 100 kilometres, the longest in the United Kingdom.
Crank Caverns is the common name of the remains of the Rainford Delph Quarry near Crank in St. Helens, Merseyside, England. It is a vast network of old tunnels and caverns, with very little known about the owners or workers of the tunnels. It appears that the main portals are much newer than the deeper tunnels found behind the tight squeeze through the gated entrance. Information in the St. Helens local history archives states that sandstone quarrying began here as early as 1700. The 1840s Ordnance Survey refers to the quarry as Rainford Old Delph. The woodland surrounding the caverns were used as a game reserve by the Earl of Derby until 1939, when they became a storage facility for ammunition for the anti-aircraft position at Crank. After the war, the caverns ceased use as a game reserve. Today, Crank Caverns are still physically accessible from a nearby public footpath, and despite the fly-tipping of rubble, shredded plastic and animal waste from the nearby Rainford Delph Farm. It is still a draw for generations of curious locals who wish to explore, many having heard the numerous local myths and legends from an early age.
Beer Quarry Caves is a man-made limestone underground complex located about a mile west of the village of Beer, Devon, and the main source in England for Beer stone. The tunnels resulted from 2,000 years of quarrying Beer stone, which was particularly favoured for cathedral and church features such as door and window surrounds because of its colour and workability for carving. Stone from the quarry was used in the construction of several of southern England's ancient cathedrals and a number of other important buildings as well as for many town and village churches, and for some buildings in the United States. Extraction was particularly intense during the Middle Ages, but continued until the 1920s. An adit to another set of workings can be seen from the South West Coast Path east of Branscombe, having been exposed by a landslip in the late 18th century. The quarry is part of the Jurassic Coast, and is a Site of Special Scientific Interest (SSSI).
The Znojmo Catacombs are a vast labyrinth of underground passageways, cellars and subcellars situated under the historic city of Znojmo, in the Czech Republic. They were initially developed for defensive purposes.
The Kőbánya cellar system or cellar system of Kőbánya, sometimes known to non-Hungarians simply as the Kőbánya Mine, or the Kobanya Mine, is an extensive network of subterranea, or underground spaces, in the 10th district of Budapest (Kőbánya), in Hungary. It is considered to be the largest cellar complex in the country. The complex as a whole started as an underground limestone quarry in a wine-growing area of present-day Kőbánya in the Middle Ages. Later wineries and beer breweries were established on the premises and they continued to use some of the underground spaces. During the Second World War, the dimensions of the complex enabled it to be used as a covert aircraft engine assembly plant and a civilian hideout. Since 2008, Kőbánya Asset Manager Jsc. organizes free guided tours annually, which introduce visitors to both the complex and the Havas Villa, one of the most notable properties connected to it. The underground complex is one of the locations that are participating in the European Heritage Days.
The Caves of Maastricht, also known as the caves of Mount Saint Peter or the Maastricht Underground, are a collection of limestone quarries in Maastricht, the Netherlands, the origins of which date back to the 13th century.
Cave diving is underwater diving in water-filled caves. 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. 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 to open water can be seen by natural light. An arbitrary distance limit to the open water surface may also be specified. Despite the risks, water-filled caves attract scuba divers, cavers, and speleologists due to their often unexplored nature, and present divers with a technical diving challenge.
