By Kenneth Freeman
‘Extreme’ is a relative word. At 250m below the surface of the ocean the pressure is 26 times higher than at the surface. This is about as deep as a human has ever free-dived, but is far too shallow and at too low a pressure for the blobfish that lives comfortably around 1km deep.
Pressure isn’t as intuitive to us as, say, temperature. The few times we notice it could be feeling your ears pop on takeoff as the cabin pressure quickly (and only slightly) drops, or feeling the building pressure as you dive towards the bottom of a pool.
The standard scientific unit for pressure is the Pascal (written Pa); typical atmospheric pressure (1 atmosphere) is around 1×105 Pa (100 kPa), the pressure at the top of Everest is about a third of that and the pressure at the bottom of a 6m deep pool is around 160 kPa.