The sea has a shape

Sea level is neither flat nor fixed. Four films about the height of the ocean surface.

Sea level sounds like a single number. Measured from orbit, it turns out to be a surface with hills and hollows tens of metres apart, small bulges that come and go with the heat in the water, and a slow rise underneath everything. None of this can be seen from a beach. Each of these films makes one part of it visible.

Start with the geoid, the shape the ocean would take if it were perfectly still. Then watch the real surface move away from that shape over a single year. The El Niño cutaway goes below the surface to show the warm water that pushes it up. The wave tank closes the series by setting the year-to-year detail aside and showing only the long trend since 1993.