North America's Appalachians and some mountains in Scotland and Scandinavia are remnants of the same range, born hundreds of millions of years ago as Pangaea came together. Many geologists think it may have reached heights comparable to the Himalayas. Erosion has since ground it down to rounded hills topping out around 2,000 m.
On 27 August 1883, the eruption of the Indonesian volcano Krakatoa was heard as far away as Rodrigues Island, nearly 4,800 km away. Its pressure wave was picked up by barometers worldwide and circled the globe several times. The tsunamis that followed killed more than 36,000 people.
The deepest known point in the ocean, Challenger Deep, lies roughly 10,900 m below the Pacific surface. Drop Everest in and its summit would still sit about 2 km underwater. Down there, the pressure is more than 1,000 times what you feel at sea level, roughly a tonne pressing on every square centimetre.