Beneath the Swedish capital lies an intricate web of underground train lines. More than 90 of the 100 stations in the 110km tunnel system, sometimes referred to as “the world’s longest art gallery”, have been decorated with paintings, installations, mosaics and sculptures by 150 artists since the 1950s. After spending a couple of weeks exploring arctic Norway and Sweden, London-based travel photographer Conor MacNeill headed underground to capture images of the metro stations. Here: A rainbow arcs over a girl on the platform of Stadion station. (Photo by Conor MacNeill/The Observer)

A tourist take a photograph of a sulphur lake in the Danakil Depression on January 23, 2017 near Dallol, Ethiopia. The depression lies 100 metres below sea level and is one of the hottest and most inhospitable places on Earth. Despite the gruelling conditions, Ethiopians continue a centuries old industry of mining salt from the ground by hand in temperatures that average 34.5 degrees centigrade but have risen to over 50 degrees. (Photo by Carl Court/Getty Images)

Dalsnibba is a mountain in Stranda Municipality in More og Romsdal county, Norway. It is located at the end of the Geiranger valley, about 21 kilometres (13 mi) south of the village of Geiranger and the Geirangerfjorden. The 2-square-kilometre (0.77 sq mi) lake Djupvatnet lies directly to the southeast of the mountain. The mountain is located very near the county border with both Oppland and Sogn og Fjordane counties, in the southeastern part of Møre og Romsdal county.

Chinese folk artists perform the lion dance at a temple fair to celebrate the Lunar New Year of Dragon on January 22, 2012 in Beijing, China. Falling on January 23 this year, the Chinese Lunar New Year, also known as the Spring Festival, which is based on the Lunisolar Chinese calendar, is celebrated from the first day of the first month of the lunar year and ends with Lantern Festival on the Fifteenth day. (Photo by Feng Li/Getty Images)

Find out what 2014 has in store for you and your cash. Provided by Russell Grant Horoscopes. (Photo by Toma Petrovic)

Emily Blincoe is an artist from Austin, Texas. Apparently, she likes to collect and classify things. This is cute, what a sugar overdose.

That's exactly what Vionnet's "Photo Opportunities" series does: takes hundreds of tourist photos of iconic landmarks, superimposes them into semi-transparency, and lets a dreamlike meta-image emerge.

What do superheroes do when they’re not busy fighting bad guys and saving the world from destruction? Perhaps they’re drawing strength alone in the peace and quiet of the great outdoors. That’s the premise of French photographer Benoit Lapray‘s photo-manipulation series “The Quest for the Absolute.”