Kendall Jenner (R) attends Casamigos Halloween party at CATCH Las Vegas at ARIA Resort & Casino on October 27, 2018 in Las Vegas, Nevada. (Photo by Bryan Steffy/Getty Images for Casamigos)

Jacob's Well is a perennial karstic spring in the Texas Hill Country flowing from the bed of Cypress Creek, located northwest of Wimberley, Texas. The twelve foot (four meter) diameter mouth of the spring serves as a popular swimming spot for the local land owners whose properties adjoin Cypress Creek. From the opening in the creek bed, Jacob's Well cave descends vertically for about thirty feet (ten meters), then continues downward at an angle through a series of silted chambers separated by narrow restrictions, finally reaching a depth of one hundred and twenty feet (forty meters). Until the modern era, the Trinity Aquifer-fed natural artesian spring gushed water from the mouth of the cave, with a measured flow in 1924 of one hundred and seventy gallons per second (six hundred and forty liters per second) discharging six feet (two meters) into the air. The spring is the greatest source of water recharging the Edwards Aquifer.

“Cheddar Gorge is a limestone gorge in the Mendip Hills, near the village of Cheddar in Somerset, England. The gorge is the site of the Cheddar show caves, where Britain's oldest complete human skeleton, Cheddar Man, estimated to be 9,000 years old, was found in 1903. Older remains from the Upper Late Palaeolithic era (12,000–13,000 years ago) have been found. The caves, produced by the activity of an underground river, contain stalactites and stalagmites”. – Wikipedia

Photo: A general view of Cheddar Gorge is seen on March 22, 2012 in Cheddar, England. With only a few months to go until the opening ceremony of the London 2012 Olympic games, Britain's tourist industry is hoping to benefit from the influx of athletes, officials and visitors. (Photo by Matt Cardy/Getty Images)

Dario Sammartino, of Italy, competes at the final table during the World Series of Poker at the Rio hotel-casino in Las Vegas Sunday, July 14, 2019. (Photo by Steve Marcus/Las Vegas Sun via AP Photo)

People look at the “Dragon de Calais” by Francois Delaroziere and La compagnie La Machine during a rehearsal in the harbour of Calais, France on October 30, 2019. (Photo by Pascal Rossignol/Reuters)

Assi Mbengue nibbles as she prepares for the start of Las Palmas' Carnival Queen ceremony in Las Palmas, Spanish Canary Island of Gran Canaria, February 24, 2017. (Photo by Borja Suarez/Reuters)

The lava of the Cumbre Vieja volcano reaches the door of a tattoo shop in La Laguna neighborhood, on the Canary Island of La Palma, Spain, December 14, 2021. (Photo by Borja Suarez/Reuters)

Discovered in 1952 by French bio-speleologist Henri Coiffait, the waterfall and accompanying sinkhole were fully mapped in the 1980s by the Spéléo club du Liban. The cave is also known as the "Cave of the Three Bridges." Traveling from Laklouk to Tannourine one passes the village of Balaa, and the "Three Bridges Chasm" (in French "Gouffre des Trois Ponts") is a five-minute journey into the valley below where one sees three natural bridges, rising one above the other and overhanging a chasm descending into Mount Lebanon. During the spring melt, a 90–100-metre (300–330 ft) cascade falls behind the three bridges and then down into the 250-metre (820 ft) chasm. A 1988 fluorescent dye test demonstrated that the water emerged at the spring of Dalleh in Mgharet al-Ghaouaghir.