Roughly 700 to 640 million years ago, glaciers reached regions that lay near the equator at the time, as glacial deposits from that era show. Many geologists think the planet was then almost entirely encased in ice, perhaps for millions of years. Volcanic gases building up in the atmosphere would eventually have thawed it out.
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.