Ocean

Consequential and out of sight. The ocean's systems run continuously, affect everything, and are almost never observed directly.

Hold in mind a system you cannot see, and ask what depends on it.

Most subjects here have a place, so geography usually leads. Across these 5, graph most often leads.

1. 01
   Descent: Surface to Hadal Zone

   Almost nothing known about the deep ocean is an observation; it is a reading. The zone boundaries are agreements, the food budget is an estimate with a region attached, and the depth of the deepest place on Earth still depends on which instrument returned it.

   7 chapters · 18 objects · graph led

2. 02
   Blue Whale Migration

   The largest animal that has ever lived is a specialist that cannot be fed by ordinary seawater — and because it must go where its smallest prey has already packed itself together, so could the fleets, and so must the instruments. Where a blue whale can be described at all is a map of where things concentrate.

   9 chapters · 30 objects · timeline led

3. 03
   Ocean Currents

   Ocean circulation is described with far more confidence than it is watched: two independent engines that are routinely mistaken for one, a circuit of roughly a thousand years, and — as the whole empirical basis for saying it is changing — twenty-two years of continuous measurement at a single latitude.

   8 chapters · 28 objects · graph led

4. 04
   The Cables Beneath

   The physical internet is a small number of corridors chosen by constraints that have barely moved since the telegraph, mended by a fleet nobody keeps a register of, and protected by a convention written for Morse code — which is why every failure large enough to be noticed is a failure of geography rather than of technology.

   7 chapters · 33 objects · graph led

5. 05
   Titanic

   Titanic is the clearest case in the modern record of a system that was compliant and still lethal — and of a place, found seventy-three years later, settling an argument that testimony could not.

   8 chapters · 31 objects · timeline led