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.

Canada's Yuri Nazarkin carves Star Wars character C-3PO (R) and R2-D2 for the ice sculpture festival in Liege, Belgium, November 13, 2015. (Photo by Eric Vidal/Reuters)

A reindeer is seen as people visit ice sculptures illuminated by coloured lights at the Harbin Ice and Snow Festival to celebrate the new year in Harbin on January 4, 2017. (Photo by Nicolas Asfouri/AFP Photo)

A visitor celebrates after attending a bare hand fishing event in a frozen river during the Hwacheon Sancheoneo Ice Festival at Hwacheon-gun, Gangwon province, South Korea, 09 January 2016. The festival runs under the theme “Unfrozen Hearts, Unforgettable Memories” from 09 January to 31 January 2016. (Photo by Jeon Heon-Kyun/EPA)

In Jukkasjärvi, a village a few miles east of Kiruna, the proprietors of one hotel begin planning for a winter ice festival in March. That’s when they begin collecting some 5,000 tons of ice from the River Torne in order to prepare the Icehotel, the world’s coolest place to stay. Options for overnight stay include snow rooms, ice rooms, art suites, and the Northern Lights room, all of which range from about $300 to $900 per night. But the deluxe suite’s the only way to go. These rooms come with a critical amenity: heated ensuite bathrooms and saunas. Here: A man walks into a room in the Ice hotel in Jukkasjarvi, Sweden, December 16, 2015. (Photo by Ints Kalnins/Reuters)

A church made entirely from ice is seen during the night at Balea Lac resort in the Fagaras mountains January 29, 2015. (Photo by Radu Sigheti/Reuters)