This article is taken from guardian.co.uk writeen by Charlotte Boan

Our small wooden vessel rocked gently on the water, revealing little of the wild currents sweeping over the coral reefs below. On the signal of our experienced dive guide Arun, we rolled off the boat and descended into the cobalt ocean.

Flying with the fast water flow, we raced past a forest of brightly coloured giant gorgonian fans and traversed through a labyrinth of large volcanic boulders. Every few minutes we clung to these rocks to watch tiny creatures taking shelter in the coral reef, and to stare into the blue. It wasn't long before a blacktip reef shark appeared. The sleek figure moved closer, up to 10m away, before disappearing into the depths. It was a thrilling hour of high-energy diving.

I was on the northernmost edge of Pulau Weh, a remote jungle island off Sumatra. Once part of the Sumatran mainland, Pulau Weh became separated during the last volcanic eruption more than a million years ago. It is surrounded by healthy and vibrant coral reefs, and its waters harbour a diverse mix of Indo-Pacific marine life.