Guest post by Chris Leadbeater
It flits past my mask in a haze of azure and yellow, its flanks paint-box bright. ‘Flits’ may be the wrong word. ‘Cruises’ would be better, because this parrotfish is so large that it looks like it must have the turning radius of an ocean liner. Then – as if to contradict my uncharitable thought – the beast suddenly changes direction with a deft flick of its huge tail, and vanishes into the deep.