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.

A general view shows the Krasnoyarsk hydro-electric power station on the Yenisei River near the Siberian city of Krasnoyarsk, Russia, January 13, 2016. The power plant, owned by EuroSibEnergo company, part of En+ Group, with a generating capacity of 6,000 megawatt (MW), has a ferro-concrete dam 124-metres high and 1065-metres long and is the second largest Russian hydroelectric power station. About 85% of the energy generated is intended for the Rusal Krasnoyarsk aluminium smelter, according to representatives of the power station. (Photo by Ilya Naymushin/Reuters)

A Buddhist monk salvages a statue of a Buddhist deity from a monastery around the famous Swayambhunath stupa after it was damaged by Saturday's earthquake in Kathmandu, Nepal, Thursday, April 30, 2015. In mere seconds, Saturday's earthquake devastated a swathe of Nepal. Three of the seven World Heritage sites in the Kathmandu Valley have been severely damaged, including Durbar Square with pagodas and temples dating from the 15th to 18th centuries, according to UNESCO, the United Nations cultural agency. (Photo by Niranjan Shrestha/AP Photo)

The moon rises over people gathered on Glastonbury Tor ahead of tomorrow's Blue Moon on July 30, 2015 in Somerset, England. The full moon appearing on July 31 will be what's called a Blue Moon, which refers to the second of two full moons appearing in the same calendar month. The last time this happened was in 2012 and there isn't due another until 2018. (Photo by Matt Cardy/Getty Images)

Surfer Arlen Macpherson sits on his board, which has an electronic shark repellent device installed, at Sydney's Bondi Beach in Australia, August 18, 2015. A spate of shark attacks in Australia has left some of world's top surfing beaches deserted and many people having second thoughts about taking a swim as the summer approaches. Macpherson paid A$390 for a device embedded in his surf board to repel sharks by emitting an electronic force field that overpowers its sensing organs. (Photo by David Gray/Reuters)

A protestor offers prayers on the second day of a demonstration demanding Prime Minister Najib Razak's resignation and electoral reforms in Kuala Lumpur on August 30, 2015. Tens of thousands of Malaysians swarmed central Kuala Lumpur on August 29, to call for the prime minister's ouster over corruption allegations and demand broader reforms, defying warnings by police who had declared the rally illegal. (Photo by Mohd Rasfan/AFP Photo)

Dancer Megan changes costume as she performs in the review “Feerie” at the Moulin Rouge in Paris, France, July 3, 2018. Each show requires 1,000 outfits, all crafted in the workshops that have been supplying the Moulin Rouge for decades. Each dancer has to make between 10 and 15 costume changes per show, with about 90 seconds to complete each one before they have to be back out on stage. (Photo by Philippe Wojazer/Reuters)

Children play underneath Jacaranda trees lining a street in the capital Harare, Zimbabwe, Friday, October 11, 2019. Zimbabwe now has the world's second highest inflation after Venezuela, according to International Monetary Fund figures. The economy has been on a downward spiral for more than a year as hopes fade that Mugabe's successor and former deputy, President Emmerson Mnangagwa, will deliver on his promises of prosperity. (Photo by Tsvangirayi Mukwazhi/AP Photo)