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.

Cuban migrant Yamilen Arbelo, 40, walks down a hill as she crosses the border from Colombia through the jungle into La Miel, in the province of Guna Yala, Panama November 29, 2015. According to local authorities in La Miel, some 100 to 150 Cubans have been entering Panama from Colombia every day for the last three months. Scores of Cubans have come to Panama as they seek overland passage towards the United States fearing a recent detente between Washington and Havana could end their preferential treatment. (Photo by Carlos Jasso/Reuters)

Environmental activist Rob Greenfield walks around Beverly Hills, California on May 16, 2022 wearing a suit filled with every piece of trash he has generated living and consuming like a typical American for one month to raise awareness about how much garbage just one person generates. (Photo by Robyn Beck/AFP Photo)

Merit Prize Winner: “A Well Earned Rest in the Sahara”. This photo of Moussa Macher, our Tuareg guide, was taken at the summit of Tin-Merzouga, the largest dune (or erg) in the Tadrat region of the Sahara desert in southern Algeria. Moussa rested while waiting for us to finish our 45-minute struggle to the top. It only took ten minutes of rolling, running, and jumping to get back down. The Tadrat is part of the Tassili N'Ajjer National Park World Heritage area, famous for its red sand and engravings and rock paintings of cattle, elephants, giraffes, and rhinos that lived there when the climate was milder. Photo location: Summit of Tin-Merzouga, Tadrat, Tassili N'Ajjer National Park, Algeria. (Photo and caption by Evan Cole/National Geographic Photo Contest)

Camp director and “duck walk” inventor (Rodin Gilbert Flores, 2nd R) teaches aspiring beauty queens how to “duck walk” at a beauty boot camp in Manila in this picture taken on March 8, 2015. From wading in muddy Philippine rice paddies, former housemaid Janicel Lubina now struts down runways for the country's top designers, and is poised to be crowned among the world's most beautiful. Lubina is a star recruit in one of Manila's beauty pageant boot camps, where shy, lanky teenage girls from remote farming provinces are transformed into poised Barbie dolls who can preach about world peace in six-inch heels. (Photo by Noel Celis/AFP Photo)

X Factor and Celebrity Big Brother starlet Chloe Khan is seen working up a sweat at her luxury home on August 30, 2016. The CBB star squeezed into a pair of super-tight leggings and a teeny crop top for a very public workout. She may be a self-made millionaire, but life wasn't always so good for Chloe Khan. The Celebrity Big Brother star, 25, has revealed she was brought up in poverty as a child in Wakefield, West Yorkshire, UK. Chloe lived with her mother on a council estate before she auditioned for the X Factor and became a playboy model. (Photo by Palace Lee)

These goats threw caution to the wind and scaled this Argan tree right to the very top, even balancing on the most unsturdy of branches. It looks like a bit of a baa-lancing act, but the goats hooves are perfectly adapted to climbing the trees, where they graze on the Argan fruit. Amateur photographer Burak Senbak, 51, took these photos whilst travelling through Morocco in July 2016. Burak is originally from Turkey and works as a mechanical engineer, but has pursued his passion for photography for 10 years. Intrigued by the sight of goats in a tree, Burak couldnt resist the opportunity to take some photos, and said the goats proved a perfect subject. (Photo by Burak Senbak/Caters News)

In this Wednesday, August 21, 1991 file photo, appreciative muscovites hand bread, sausages and flowers to a Soviet tank's driver who helped stop the failed hardline coup in Moscow, Russia. When a group of top Communist officials ousted Soviet leader Mikhail Gorbachev 30 years ago and flooded Moscow with tanks, the world held its breath, fearing a rollback on liberal reforms and a return to the Cold War confrontation. But the August 1991 coup collapsed in just three days, precipitating the breakup of the Soviet Union that plotters said they were trying to prevent. (Photo by Czarek Sokolowski/AP Photo/File)