“Rivers Forgotten” is a journey through the passages and portals of the underground waterways that lie unseen below cities. Self-taught photographer Jeremy Kai brings these forgotten landscapes to light. Photo: Beneath the Toronto area, 2011. (Photo by Jeremy Kai)

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).

Like a scene from a fantasy movie, a dilapidated room that appears to have been literally ripped out of a building remains suspended in mid air above Nantes, France. Its walls were torn apart, revealing bricks below the plaster, and wood floors reveal the joists inside. The floating room is accessible via a ladder. The gravity defying surreal installation is the work of Argentinean artist Leandro Erlich. The large-scale piece, called “Monte-meubles – L’ultime déménagement” (literally - The Furniture Lift – The Ultimate Moving Out), was created for the biannual Le Voyage a Nantes, an art festival which turns the entire French city into an art gallery.

Kim Leuenberger is a Swiss photographer with a love for travel. She believes we are all explorers and is currently studying photography at University of the Arts London. These photos are from her series, “Traveling Cars Adventures”. Photo: “Lover of the Light”, Red Union Jack Mini Cooper, Bern, Switzerland, October 2012. (Photo by Kim Leuenberger)

A Palestinian youth practices his parkour skills at Shati refugee camp in Gaza City April 27, 2014. (Photo by Mohammed Salem/Reuters)

Inside the Afar Triangle in Ethiopia’s Danakil desert, camel caravans are used to carry salt. For centuries, the essential mineral has been mined by the Afar people, known for their ability to withstand extremes. The terrain is rugged, travelers are scarce and so are motor vehicles, where the average annual temperature is the highest in the world, and can rise to 122 degrees Fahrenheit, 50 degrees Celsius. (Photo by Ziv Koren/Polaris)

“Just hanging out”. As full autumn hits the valley of Hallingdal in Norway, this bear chills out in a tree which seems to barely cover its weight. Photo location: Flå, Hallingdal, Norway. (Photo and caption by Jorgen Tharaldsen/National Geographic Photo Contest)

Six Flags New Orleans, also abbreviated to SFNO, is an abandoned theme park in New Orleans, Louisiana, that has been closed since just before Hurricane Katrina struck in August 2005 and is currently owned by the city of New Orleans. Six Flags had previously owned the park since March 2002, but after assessing the devastation caused by Hurricane Katrina and the related exorbitant expenses of repairing the damage, sought to terminate their 75-year lease with the city, beginning in July 2006 and finally succeeding in September 2009. The park is located in Eastern New Orleans, in the Ninth Ward of the city, off Interstate 10. Despite various announced plans to redevelop the site, as of 2014, it is still an abandoned amusement park in extremely poor condition. It is a well-known urban exploration destination.