A woman rides a mechanical bull before participating in the 4th annual Running of The Bulls October 15, 2011 in Cave Creek, Arizona. (Photo by Joshua Lott/Getty Images)

Cave Diver, Anhumas Abyss, Bonito, Brazil: The Anhumas Abyss is an underground cavern with a crystal-clear lake below, more than 260 feet (79 m) deep. A visitor must enter through a narrow opening at the top of the chamber and rappel into the cave. Snorkeling and scuba diving in the lake reveal amazing scenery. Distinctive, conical limestone stalagmites and stalactites occupy the lake and the surrounding area, some reaching 65 feet (20 m) high. (Photo by Marcio Cabral/Nature’s Best Photography Awards 2017)

School cheerleaders wearing protective masks pose for a photo as fellow students arrive for classes on the first day of school in Miami-Dade County at Barbara Goleman Senior High School, in Miami, Florida, August 23, 2021. (Photo by Marco Bello/Reuters)

Secondary school graduates play in a fountain as they celebrate the last day of school, traditionally called the “last bell” in central Kiev, Ukraine on May 31, 2019. (Photo by Valentyn Ogirenko/Reuters)

Pupils wearing face masks wait for the opening of their primary school on the first day of the new school year, in Ouagadougou, on October 1, 2020. (Photo by Olympia de Maismont/AFP Photo)

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.

A Hindu devotee in a trance on their pilgrimage to the Batu Caves temple in Kuala Lumpur, Malaysia on January 28, 2018. Malaysian Hindu participate in the annual Hindu thanksgiving festival in which devotees subject themselves to painful rituals in a demonstration of faith and penance held in honour of Lord Murugan, Hindu in Malaysia celebrated Thaipusam begin on Jan 28 until 31 this year. (Photo by Aflo/Rex Features/Shutterstock)

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.