Deep ocean trenches plunge far deeper than the height of the tallest mountains on land.

The longer version

Plate boundaries bend downward where one slab slides beneath another, and extreme depths collect in those narrow scars rather than in open basins. Because the planet has a fixed radius, material forced down must be matched by crust pushed up, which is why mountain belts rise alongside them.

Pressure down there multiplies by roughly one atmosphere every ten metres, yet specialised animals persist by keeping their internal chemistry stable. Sediment washed off the continents drifts in and fills the troughs. Measured from rim to floor, the vertical drop exceeds the height of the tallest peaks on land.

Where this entry sits

Oceans and Sea Life looks at the salt water that covers most of the planet, from crashing waves and tides to the darkest deep-sea trenches. Expect notes on coral, fish, whales, sharks, jellyfish, shells, and the strange creatures that live far below the surface. The full list sits on the Oceans and Sea Life page, where every entry is listed in order.