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 also known as 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. Sink, and 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 or, as in the 2018 Thai cave rescue, other cave users. 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.
Kartchner Caverns State Park is a state park of Arizona, United States, featuring a show cave with 2.4 miles (3.9 km) of passages. The park is located 9 miles (14 km) south of the town of Benson and west of the north-flowing San Pedro River. Long hidden from view, the caverns were discovered in 1974 by local cavers, assisted by state biologist Erick Campbell who helped in its preservation.
Kents Cavern is a cave system in Torquay, Devon, England. It is notable both for its archaeological and geological features. The cave system is open to the public and has been a geological Site of Special Scientific Interest since 1952 and a Scheduled Ancient Monument since 1957.
Russell Cave National Monument is a U.S. national monument in northeastern Alabama, United States, close to the city of Bridgeport. The monument was established on May 11, 1961, when 310 acres (1.3 km2) of land were donated by the National Geographic Society to the American people. It is now administered and maintained by the National Park Service. The national monument was listed on the National Register of Historic Places on October 15, 1966.
A cenote is a natural pit, or sinkhole, resulting when a collapse of limestone bedrock exposes groundwater. The term originated on the Yucatán Peninsula of Mexico, where the ancient Maya commonly used cenotes for water supplies, and occasionally for sacrificial offerings. The name derives from a word used by the lowland Yucatec Maya—tsʼonoʼot—to refer to any location with accessible groundwater.
The Mitchell Caverns, within the Mitchell Caverns Natural Preserve, are three solution limestone caves, only two of which are open to the public, located on the east side of the Providence Mountains at an elevation of 4,300 feet (1,300 m), within the Providence Mountains State Recreation Area. The caverns are located in the Mojave Desert, in San Bernardino County, California.
The Delaware Basin is a geologic depositional and structural basin in West Texas and southern New Mexico, famous for holding large oil fields and for a fossilized reef exposed at the surface. Guadalupe Mountains National Park and Carlsbad Caverns National Park protect part of the basin. It is part of the larger Permian Basin, itself contained within the Mid-Continent oil province.
Cave of the Winds is a cave in the Pikes Peak region of Colorado. It is located just west of Colorado Springs on U.S. Highway 24, near the Manitou Cliff Dwellings. Tours of the complex of caves are given daily.
Manatee Springs State Park is a Florida State Park located six miles west of Chiefland on SR 320, off US 19. Manatee Spring is a first magnitude spring that flows directly into the Suwannee River by way of a short run. Present also are swamps and hardwood wetlands along the Suwannee, along with many sinkhole ponds, including one with a cave 90 feet below the ground that connects to a popular divers' destination known as the Catfish Hotel.
The Ozark National Scenic Riverways is a recreational unit of the National Park Service in the Ozarks of southern Missouri in the U.S.
Lewis and Clark Caverns State Park is a 3,000-acre (1,200 ha) public recreation and nature preservation area located twelve miles (19 km) east of Whitehall in Jefferson County, Montana. The state park includes two visitor centers, ten miles of hiking trails, a campground, and its namesake limestone caverns. The Lewis and Clark Caverns Historic District was placed on the National Register of Historic Places in 2018.
Carlsbad Caverns National Park is a national park of the United States in the Guadalupe Mountains of southeastern New Mexico. The primary attraction of the park is the show cave Carlsbad Cavern. Visitors to the cave can hike in on their own via the natural entrance or take an elevator from the visitor center.
The Lost River is a river that rises in Vernon Township, Washington County, Indiana, and discharges into the East Fork of the White River in Lost River Township, Martin County, Indiana. The river's unusual hydrology has led to two of its features being named as National Natural Landmarks.
Cedars of Lebanon State Park is a state park in Wilson County, Tennessee, in the southeastern United States. It consists of 900 acres (364 ha) situated amidst the 9,420-acre (3,810 ha) Cedars of Lebanon State Forest. The park and forest are approximately 10 miles (16 km) south of Lebanon, Tennessee.
The Blue Hole of Santa Rosa, or simply the Blue Hole, is a circular, bell-shaped pool or small lake located along Route 66 east of Santa Rosa, New Mexico that is a tourist attraction and swimming venue, and one of the most popular dive destinations in the US for scuba diving and training. The Blue Hole is an artesian well and cenote that was once used as a fish hatchery.
Indiana Caverns is part of the Binkley Cave system near Corydon, Indiana.
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.
