Gorner Glacier, Switzerland

Photograph by Robbie Shone

Beneath the stars, two scientific explorers descend into the icy depths of a moulin on the Gorner Glacier in Switzerland. The freshly exposed rock above the glacier on the left-hand side shows how the ice has melted under an increasingly warm world. These explorers are mapping the changes taking place beneath the surface. Their work must be carried out at night because high daytime temperatures create vast amounts of meltwater, making exploration difficult and dangerous.

Shepherd's Cave, Afghanistan

Photograph by Matthieu Paley

Kyrgyz men seek shelter in a shepherd’s cave during their annual journey from their mountainous homeland in remote Afghanistan to the nearest trading village in Pakistan, an icy, five-day trek. They will barter livestock, wool, and dairy products for everything from tea to television sets

Climber, Queen Maud Land

Photograph by Cory Richards

Suspended from an anchor in the rock hundreds of feet above the ice and snow, Mike Libecki hauls himself up a granite tower in Antarctica's remote Queen Maud Land.

Hikers Camping, Glacier Bay National Park

Photograph by JK Putnam

My wife and I paddled up the west arm of Glacier Bay and back on an eight-day kayak trip in Alaska’s Glacier Bay National Park. We were on our own for the majority of the trip. We went days without seeing other people, but we never felt alone. This trip strengthened the already well-founded bond between us. I took this photo so that we would always have something to remind ourselves of this experience and how much closer we grew during it.

Manta Ray and Snorkeler, Australia

Photograph by Violeta Jahnel

A snorkeler appreciates the beauty of a giant manta ray in Ningaloo Reef, off Australia’s west coast.

Moai, Easter Island

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Photograph by Randy Olson

Their backs to the Pacific, 15 restored moai stand watch at Ahu Tongariki, the largest of Easter Island's ceremonial stone platforms. Rapanui artisans carved the moai centuries ago from volcanic rock at a quarry a mile away. By the 19th century all of Easter's moai had been toppled—by whom or what is unclear. In 1960 these moai were swept inland by a tsunami, which fractured some (left).

Sunset, Mount Everest

Photograph by Cory Richards

The sun sets over the west shoulder of Mount Everest (right) and Mount Nuptse.

Kayakers, Maui

Photograph by Ron Dahlquist

There is an incredible coral bloom off the village of Olowalu on Maui's south shore. I've seen the coral from a helicopter numerous times and always thought it would photograph beautifully, especially if I could arrange for some kayakers to be paddling in and around the coral to add scale to the scene.

Both Island, Antarctica

Photograph by Nancy Dowling

Taken at Booth Island in Antarctica.

Reef Manta Ray, Bali

Photograph by Andrea Marshall

"On one special day we encountered dozens of reef manta rays feeding at the surface in Nusa Penida," Marine Megafauna Foundation cofounder and National Geographic explorer Andrea Marshall says. "When these giant animals feed they are distracted, and snorkelers can approach them quite closely without disturbing them. It is almost like they go into a trance.

"This individual spent about a half an hour with us, in quite shallow water, weaving in and out between us while feeding on densely concentrated plankton in the surface waters," she says. "As it approached me it reared up a bit and flashed its ventral surface (belly) at me, giving me a glimpse of its natural spot patterning on its underside, which we use to identify between different rays."

Marshall and her team recently created Manta Matcher, an automated online manta ray database. It "stores the patterning of each manta ray sighted across the world and automatically checks for a match every time a new entry is uploaded," Marshall says. "This system will allow researchers to follow the lives of these elusive animals and learn more about their movements and behavior over time."

Mount Everest, Nepal

Photograph by Nikolay Radosnov

A Sherpa carries luggage in the vicinity of the Tengboche Monastery, Nepal.

Middle Atlas Mountains, Morocco

Photograph by Vlad Min

The inclusion of the motorcycle in this image is essential to understanding the scale of the setting, and that detail is what makes this shot work. Also, a person riding a motorcycle is a far more effective detail than a passing car would have been; we feel the emptiness of the long, winding road even more acutely.
Although the image has great light and the curves make for a graceful composition, it’s not complete without the motorcycle. Getting a shot like this may require a long wait, but a key detail, however small, may make the shot.

Kathmandu Stupa, Nepal

Photograph by Susheel Shrestha

The Bodhnath Stupa is a World Heritage site in Kathmandu, Nepal. Kathmandu is for many a gateway to Mount Everest.

Salar de Uyuni, Bolivia

Photograph by George Steinmetz

On the eastern margin of Salar de Uyuni in Bolivia, expedition cars attempt to cross the flats after flooding from heavy March rains.

Claustral Canyon, Australia

Photograph by Carsten Peter

Veteran guide John Robens (at far left) leads a soggy team through a moss-covered passage in Claustral Canyon, a few hours' hike from their exit point. Canyoneering is all about the serendipity of discovery, he says. "You walk for miles and suddenly you find yourself in this magical spot."

Ice Cave, Slovenia

Photograph by Peter Gedei

Ice caves are melting; that's a fact. In an ice cave on the mountain of Stojna near Koƒcevje, Slovenia, the situation has been very dramatic for years. Since 1991 almost four meters of ice have disappeared in the entrance chamber, but at the bottom of the cave emerges a new one. The entrance of this cave faces toward the southeast, which is not common for ice caves. Because of that, the whole area around the entrance is important, and even one cut-down tree can cause huge losses of ice in the cave.

Kali Gandaki River, Nepal

Photograph by Cory Richards

Climbers and scientists follow a trail above the Kali Gandaki River in Nepal's remote Mustang region. More than 60 feet above are rows of unexplored man-made caves dug centuries ago. There may be thousands in the region.

Cave, Nepal

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Photograph by Cory Richards

To reach a series of caves dug into a cliff 155 feet above the valley floor, Matt Segal scales a rock face so fragile it often breaks off to the touch. Linked by a ledge, the 800-year-old caves, empty now, may once have stored manuscripts.

Warren Cave(Mount Erebus), Antartica

Photograph by Carsten Peter

A mix of ropes and ladders eases access to Warren Cave, a labyrinth of passages melted from the ice by the volcano's heat. Small currents of air probably cause the scalloping around the cave's entrance.

Caucasus Mountain, Russia

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Photograph by Vittorio Sella

Two men look toward mountain peaks in the Caucasus in this photo by Vittorio Sella that dates to around 1896.
Sella was a mountaineer and a pioneering high-altitude photographer who captured images from many of the world’s great mountain ranges.