Mountaineer and filmmaker David Breashears has climbed to the summit of Mt. Everest five times, but when he accompanied FRONTLINE correspondent Martin Smith into the Himalayas in 2007 for the film Heat, he had a different mission: to photograph Everest from the same vantage point where British explorer George Mallory shot an iconic 1921 photo of the main Rongbuk glacier. With Mallory’s photo in hand, he set out to to see how much had changed.

“I wasn’t prepared for the amount of change that I saw,” says Breashears of the wide river of ice that had retreated more than half a mile. “I thought, why didn’t I know more about this?” That revelation is what led him to embark on a broader project to document the changes taking place in a glacier-rich region that’s a vital source of water for the major rivers of Asia.

The result is a stunning interactive, panoramic image that lets you explore the south side of Everest in intimate detail and compare changes for yourself — without the climb.

With the help of xRez Studio, Breashears and his non-profit organization GlacierWorks created a 4 billion pixel image out of hundreds of high-resolution still photos. Users can navigate by themselves or by zooming in on the green “hot spots” that include photo galleries comparing contemporary images with historic photos. (Learn more about how to navigate within the image here and also explore the Khumbu Glacier image.)

“We’ve given people a way to explore the iconic landscape of Everest in a way they’ve never had the opportunity to do before,” says Breashears of the project that has already brought 300,000 visits to the GlacierWorks website. “They can explore and choose the path of their own choice. They can go up 22,000 feet and wander into the base camp.”

The project, ongoing since 2007, also yields valuable insights into the effects warming is having on the more than 50,000 glaciers in the greater Himalayan region.

“What we’ve really found is that there’s a lot of misunderstanding about how climate change is affecting the region, and what its outcomes will be for people, for poverty,” says Breashears. “It’s such a big complex system that needs a lot more science, and we we want to start important conversations and dialogues that get people to look harder at these regions.”