A photographic record that can be measured. An ordinary underwater photograph cannot be. Nobody can say how large anything in it is, because there is no scale. Nobody can say how bright the light was, because the camera guessed. Nobody can say where the camera was, how far away, or whether it was tilted.
The method removes those unknowns not by being careful but by putting the answers in the frame. Everything else follows from that.
From those images, one kind of number. Benthic cover — benthic just means the sea floor — what proportion of the surface is hard coral, soft coral, macroalgae, turf, rubble, sand — estimated by scattering points over the frame and asking what lies under each one. Condition is not read from the frame; it is your CoralWatch survey at the station, and the Entry points to it.
And a written protocol precise enough that somebody who has never spoken to you can find your station and repeat what you did.