Salar de Uyuni (or Salar de Tunupa) is the world's largest salt flat at 10,582 square kilometers (4,086 sq mi). It is located in the Potosí and Oruro departments in southwest Bolivia, near the crest of the Andes, and is elevated 3,656 meters (11,995 ft) above mean sea level. The Salar was formed as a result of transformations between several prehistoric lakes. It is covered by a few meters of salt crust, which has an extraordinary flatness with the average altitude variations within one meter over the entire area of the Salar.

A Panasonic Toughpad is displayed during a press event at The Venetian for the 2012 International Consumer Electronics Show (CES) January 9, 2012 in Las Vegas, Nevada. CES, the world's largest annual consumer technology trade show, runs from January 10-13 and is expected to feature 2,700 exhibitors showing off their latest products and services to about 140,000 attendees. (Photo by Ethan Miller/Getty Images)

Elvis Presley tribute artist Bruce Stewart (L) of Georgian Bay, Ontario passes Lorenz Francke of Scarborough, Ontario during the four-day Collingwood Elvis Festival in Collingwood, Ontario July 25, 2015. Featuring over 120 Elvis tribute artists, it is the world's largest Elvis festival and last year hosted 30,000 visitors. (Photo by Chris Helgren/Reuters)

A woman looks at La Paz city from the Jacha Qhatu cable car station in El Alto, July 23, 2015. Bolivia already has the largest urban cable car system in the world. Now the booming country is tripling the size of the network and will soon have nine lines whizzing above the administrative capital of La Paz. (Photo by David Mercado/Reuters)

Rungis is a commune in the southern suburbs of Paris, France. It is best known as the location of the large wholesale food market serving the Paris metropolitan area and beyond, the Marché d'Intérêt National de Rungis, said to be the largest food market in the world. The name Rungis was recorded for the first time in a royal charter of 1124 as Rungi Villa. Here: swordfish are sold at the fish pavilion in Rungis International food market as buyers prepare for the Christmas holiday season in Rungis, south of Paris, December 11, 2015. (Photo by Philippe Wojazer/Reuters)

The Greenland ice sheet is a vast body of ice covering 660,235 sq miles, roughly 80% of the surface of Greenland. It is the second largest ice body in the world, after the Antarctic Ice Sheet. Some scientists predict that climate change may be near a "tipping point" where the entire ice sheet will melt in about 2000 years. If the entire 2,850,000 cubic kilometres (683,751 cu mi) of ice were to melt, it would lead to a global sea level rise of 7.2 m (23.6 ft).

Hindu pilgrims walk along a mountain path as they make their pilgrimage to the sacred Amarnath Cave, one of the most revered Hindu shrines, near Baltal, Kashmir, India. (Photo by Daniel Berehulak)

“Kumbh Mela is a mass Hindu pilgrimage in which Hindus gather at the Ganges river. The normal Kumbh Mela is celebrated every 3 years, the Ardh (half) Kumbh Mela is celebrated every six years at Haridwar and Prayag, the Purna (complete) Kumbh takes place every twelve years, at four places (Prayag (Allahabad), Haridwar, Ujjain, and Nashik). The Maha (great) Kumbh Mela which comes after 12 “Purna Kumbh Melas”, or 144 years, is held at Allahabad.

The last Ardh Kumbh Mela was held over a period of 45 days beginning in January 2007, more than 70 million Hindu pilgrims took part in the Ardh Kumbh Mela at Prayag, and on January 15, the most auspicious day of the festival of Makar Sankranti, more than 5 million participated. The previous Maha Kumbh Mela, held in 2001, was attended by around 60 million people, making it at the time the largest gathering anywhere in the world in recorded history”. – Wikipedia

Photo: Sadhus (holy men) smoke at their camp near the ritual site at Sangam, the confluence of the Ganges, Yamuna and mythical Saraswati rivers during the Ardh Kumbh Mela festival (Half Pitcher festival) January 18, 2007 in Allahabad, India. Millions of Hindu pilgrims have flocked to the largest religious gathering in the world which lasts for 45 days in northern India. The festival commemorates the mythical conflict between gods and demons over a pitcher filled with the “nectar of immortality”. Devotees believe that taking a holy dip in the Ganges at this time washes away their sins and paves the path to salvation. (Photo by Mario Tama/Getty Images)