The Arun River basin is 47 miles from Everest and runs down into the larger Koshi River system – a waterway many adventurers heading for Everest base camp will traverse en route.

The Arun river, which flows east of Everest, has long been shaping the landscape through its erosion. About 89,000 years ago, it merged with the Kosi river system in a process called drainage piracy.

Around 90,000 years ago, the Arun River changed course, eroding rock that once held Everest down. But could the mountain’s growth really be due to an old river? 'Alien oceans confirmed?': ...

But Everest is growing more than expected from this alone. Scientists now think it is because of how two nearby river systems combined. The Kosi river merged with the Arun river about 89,000 years ...

The river capture caused rapid erosion, carving the Arun Gorge. This erosion lightened the surrounding landmass, leading to the uplift of Mount Everest, which continues to rise today. GPS data ...