Since the first precise measurements in the 19th century, the average strength of Earth's magnetic field has dropped by about 9%, according to the European Space Agency. That decline sometimes fuels speculation about an imminent reversal. But the field has gone through similar fluctuations before without flipping, and nothing today allows scientists to predict a reversal anytime soon.
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.