Mount Everest was a mountain on Earth, which stood at around 8km tall. (TV: The Waters of Mars)
History
In 1953, the first humans successfully climbed Mount Everest. (TV: The Idiot's Lantern) Guests at the Time Hotel were able to travel from London in 4202 to Everest base camp in 1953, where they could stay in an unoccupied tent. The Fifteenth Doctor entered this tent from the Time Hotel on two occasions: firstly to offer the guests a ham and cheese toastie and a pumpkin latté, and secondly to retrieve some rope. (TV: Joy to the World [+]Steven Moffat, Doctor Who Christmas Special 2024 (BBC One and Disney+, 2024).)
Santiago Jones visited it during one of his journeys. (TV: Death of the Doctor)
When the Earth nearly became an ocean planet in the early 22nd century, much of Mt Everest was submerged in water. River Song recalled once fishing off the coast of Everest. (AUDIO: Kings of Infinite Space)
At some point during the 51st century, the Doctor helped carry the Mona Lisa up Mount Everest on a camel to preserve it from a war. (PROSE: The Art of Destruction)