At the centre of the planet, the inner core, a ball of iron and nickel about 1,200 km in radius, is estimated at 5,000 to 6,000 °C, comparable to the surface of the Sun. It ought to be molten, but the pressure there exceeds 3 million times that of the atmosphere, forcing the atoms to stay locked in place. Surrounding it, the outer core is liquid.
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.