Vietnam’s Son Doong cave, the largest in the world, could hold a 40-story skyscraper inside. The pristine ecosystem has its own river and jungle. Despite its size, Son Doong wasn’t discovered until 1991. It was lost again for nearly two decades and was fully explored for the first time in 2009. (Photo by Jason Speth/HuffPost)

The Maijishan Grottoes are a series of 194 caves cut in the side of the hill of Majishan in Tianshui, Gansu Province, northwest China. This example of rock cut architecture contains over 7,200 Buddhist sculptures and over 1,000 square meters of murals. Construction began in the Later Qin era (384-417 CE).

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)

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)

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.

Alexey Malina has portrayed the Seven Deadly Sins in a series of posters called Seven Sins. The black shapes bleed as the deception and dread of sin’s course evolves in one’s life. Their stamina caves to lust, wrath, envy, greed, sloth, pride and gluttony. As the New Testament warns us, “flee from evil, cling to what is good” for the patterns that follow the seven only lead to death.

“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)