In choppy waters off the coast of a beautiful tropical paradise, make sure you hang on tight to your expensive equipment.

For the past few years, I have been working with the XL Catlin Seaview Survey. This unique coral reef monitoring program launched in 2012 and has since visited over 30 countries, recording the baseline condition of coral reef ecosystems. Using a custom camera system attached to diver propulsion vehicles, we collect imagery on two-kilometre scales to establish species composition by means of semi-automated technology, without compromising the detail achieved through conventional methods. During a time of rapid ecosystem change, this type of survey is integral in monitoring how coral reef ecosystems change over time.

During my time with the survey, I have joined expeditions in almost ten countries (you can virtually dive them here), but one of the most interesting places was the Chagos Archipelago, which I visited in early 2015. If you were like me, you may never have heard of it. Its primary use is as a British-owned, US-leased military base, directly south of the Maldives in the Indian Ocean.

Being so remote, isolated and unexplored, I didn’t really know what to expect. The reefs were stunning and unlike anything I had experienced before. Kilometres of reef were composed of fascinating blends of coral genera, expanses of delicate Seriatopora and mounding fields of Galaxea in unimaginable colours. In the water column, sharks, turtles and schooling fish swam casually around us — not frightened, just curious. Every single dive, I was followed by one or two tawny nurse sharks.

It was only our second day of the survey — actually Friday the 13th — when the weather got worse in transit to our afternoon dive location. It was dark, and pouring rain. Large waves splashed over our heads as we journeyed to our site. Once we decided on an entry point for the dive, we went through our preparations, just as we had a million times before. We were being blown off the reef quickly and could no longer see the bottom.

Because the boat was rocking and it was hard to stand, we opted to put on our dive gear in the water. The team in the boat passed in my buddy’s dive gear and he started kitting up. As the team lowered in my gear, it slipped out of their hands and splashed into the water front of me, improperly inflated and strapped to 18kg of steel dive tank and weights.

I reached for my gear, missing hold of it by centimetres, and it began plummeting into the deep.

I dove down to grab it, but the buoyancy of my wetsuit kept me from going further than a few metres. Immediately, my buddy descended chasing the dive rig. He dove deeper and deeper into the blue, somewhere around 30 to 40 metres, attempting to intercept the dive gear mid water column.

But all of a sudden, there were sharks. A large school of silvertip reef sharks came from every angle around us. They began circling, darting in and out, maybe just curious or possibly more aggressive. I vividly remember one of the larger sharks singling out my buddy, approaching him over and over, and my buddy clutching his alternate air source so that, if necessary, he could deter it by spraying bubbles in its face. Although intimidating at the time, to me this encounter was also equally fascinating; there are not many places left in the world so wild.

Efforts to rescue my diving gear were eventually abandoned due to its depth and the behaviour of the sharks. To this day, my first set of dive gear, which I pieced together for $2,500 during my undergraduate studies, rests at an unknown depth in the middle of the Indian Ocean.