All through my northern youth I had dreamed of such a world: quiet bays with water the colour of jade and aqua velva, beaches so white they blinded you in the noon sun, and lazy arching coconut palms whose fronds whispered all the afternoon.

We had paddled the kayak to this perfect shore, an island full round the world from where my journey began. And ridding myself of northern winters at last, I slid beneath the surface membrane in my snorkel and mask. There in the blue column, I floated through a living world-sized aquarium: a place of bright movement and comical clowns, with darker shadows deep in the periphery of sight.

I never fail to be astounded by the diversity of life beneath the coral shore. Fish more brilliant than any tropical forest birds: colours that look too neon to be real. Parrotfish, clownfish, angelfish, and muppet-looking wrasses. Narrow torpedo-shaped half-beaks and thick groupers further down. Starfish the colour of summer skies. And beneath it all, soft white sand littered with knobby sea cucumbers and black urchins with spines vicious asknitting needles.

And the noise. Coral reefs are no pantomime, but an endless backdrop of clickings and raspings and croaking calls. Perhaps this came as the greatest surprise of all.

For an inland child raised on Jacques Cousteau specials and National Geographic, reaching the coral shores was a sort of homecoming. Years earlier I had warmed my long student winters with posters of coral shores upon my wall. At last I had arrived.