Diving during the transition into twilight is a strange and beautiful sensation. It sneaks up on you stealthily like a high cloud creeping across the sun.

At first I am simply aware of a change in mood. Some fish become scarce while others, more at home in the dark places of the sea come out into the open. My attention on the fishes and their behaviours captures my attention; masking my awareness of the fading light.

Almost by surprise I notice I really can’t see much anymore. All has become grey and ghostly. Rather than spoil the mood by turning on my lights I’ll swim back to the anchor and make my way back up the line.

I soon catch the last hint of colour and light hitting the seas above as the sun dips below the horizon and I realise just how dark it is now down here as I make my way back up to my airy sanctuary above.