A round circle of smoke coming from the mouth of the Etna volcano is seen in the sky during an eruption on the southern Italian island of Sicily April 11, 2013. Mount Etna is Europe's tallest and most active volcano. (Photo by Antonio Parrinello/Reuters)

Kelimutu is a volcano, close to the small town of Moni about 50 km to the east of Ende, Indonesia in central Flores Island of Indonesia.

“Mount Hua, or Hua Shan, or Xiyue located near the city of Huayin in Shaanxi province, about 120 kilometres (75 mi) east of Xi'an. It is one of China's Five Great Mountains, and has a long history of religious significance. Originally classified as having three peaks, in modern times the mountain is classified as five main peaks, of which the highest is the South Peak at 2,154.9 metres (7,070 ft)”. – Wikipedia

Photo: Trip to Xi'an 西安. (Photo by Grant Robinson)

This happy couple started married life on top of the world, having exchanged their vows on mount Everest. Dressed in a full suit and wedding dress, James Sissom and Ashley Schmieder spent days scaling the mountain range in order to be photographed in front of such a breathtaking backdrop. Here: James Sissom and Ashley Schmieder exchange vows on Everest. (Photo by Charleton Churchill/Caters News Agency)

The Y-40 Deep Joy is the worlds deepest pool. Y-40 is projected by Architect Emanuele Boaretto and supported by the “Boaretto Group Hotel and Resort”. The name Y-40 is inspired by mathematical symbols. “Y” is the ordinate axis of the Cartesian system and “–40” means the world's record depth or our pool- that is 40 meters underground. (Photo by Courtesy Y40 Deep Joy)

Sailors stand on the deck as the USS New York as it passes the Statue of Liberty during the start of Fleet Week May 25, 2011 in New York City. Fleet week, which has been held in New York City since 1984, celebrates the U.S. Navy and Marines Corps with a week of ship visitations and military demonstrations. Fleet Week concludes on Memorial Day with a military flyover to honor those killed while serving in the military. (Photo by Spencer Platt/Getty Images)

A Hindu worshipper throws vegetables into the crater as offerings during the Kasada Festival at Mount Bromo in Probolinggo, Indonesia's East Java province, August 1, 2015. Every year people gather for the annual festival where offerings of rice, fruit, vegetables, livestock or money are made to Hindu gods at the active volcano to ask for blessings and assure a bountiful harvest. (Photo by Reuters/Beawiharta)

A resident carries a gas canister as an ash cloud hovers above during an eruption of Mount Sinabung volcano at Tiga Serangkai village in Karo Regency, North Sumatra province, Indonesia June 24, 2015. More than 10,000 people from 12 villages, who are living around the slopes of Mount Sinabung, left their homes and moved to refugee camps, local media reported. (Photo by Reuters/Beawiharta)