Decisions about returning home suddenly disappeared as my eyes focussed on the heaving mass of marine life in front of me. Schools of fish so dense I could not catch a glimpse of whatever lay beyond. Turtles swam lazily between sea lions that darted here and there, alternately herding fish then scattering them, piercing the heart of the shoal. With a flick of a fin sea lions pirouetted and tumbled, so playful and curious. Sharks patrolled the blue, languid but lethal when prey was detected. Jacks, creole fish and brightly coloured moorish idols swayed with the swell. Parrotfish munched on coral heads beneath red clouds of cardinal fish.

The experience was like nothing I had encountered before. I had regularly dived the temperate waters of coastal Britain – beautiful in a different way – but this was something else. The adrenalin rush was unbelievable. I was hooked. Addicted.

Then I saw my first whale shark. Swept out into the blue water off the volcanic platform of Darwin Arch – and whilst carrying out a routine safety stop – an enormous shadow loomed over me.  I watched in awe as the world’s largest fish (species rather than individual!) finned toward me, passing just metres away. The only indication that it was aware of my presence was the rolling of an eye in my direction. Otherwise, it was unfazed. One minute it was there eclipsing everything in sight, and then it was gone.