In 1977, the submersible Alvin found hydrothermal vents teeming with life off the Galápagos Islands. Black smokers discovered since then spew water hotter than 350 °C, kept liquid by the immense pressure. Bacteria, giant tube worms and crabs live there through chemosynthesis, drawing energy from chemicals rather than light. Some researchers see such vents as a possible cradle of life.
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.