According to the GRACE and GRACE-FO satellites, which detect tiny changes in gravity, Greenland's ice sheet has lost an average of about 270 billion tonnes of ice per year since 2002. That is roughly 100 million Olympic swimming pools every year. This melt is now one of the leading contributors to rising sea levels.
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.