I realised I had misjudged the four-metre tides for my afternoon coral reef surveys and I was holding on for dear life to a truck-sized Porites coral colony as the outgoing tide tried to sweep me out of the lagoon and into East Africa’s busiest shipping channel.

Other than my unfortunate situation, I was enjoying a beautiful afternoon. Back on the beach, which was a tantalisingly short distance away, the palm trees swayed gently in the breeze on a white sand beach. Feeling more embarrassed than actually worried, I tried to calm my breathing through my snorkel as the water powered past me, counting each breath in an attempt to patiently wait for the tides to weaken enough so I could swim back into shore. However, until that happened, I had some time to kill, so I took a good look at the reef around me.

Coral colonies had been living and dying on this reef for thousands of years. Luckily, some corals were so large I could stretch my arms out and hold onto in the outgoing tide. It was 2009, I was a PhD student and scientist-in-training with the Coral Reef Conservation Program of the Wildlife Conservation Society (WCS). Ever since I arrived as an intern back in 2006, I had been fascinated by corals, the tiny upside-down jellyfish who live together to build vast colonies of calcium carbonate to form the backbone of every coral reef in the world. How could you not be impressed by these humble reef builders, each one beginning life as small as a poppy seed that could eventually come to build the planet’s largest living structure – Australia’s Great Barrier Reef – which is large enough even to be seen from space.

Most of the corals in the Mombasa National Marine Park were vast and brown Porites corals. It’s a tough life for coral these days. In 1998, ocean temperatures skyrocketed during an El Niño heatwave that bleached and killed nearly half of the living coral cover throughout the Western Indian Ocean. To study long-term reef recovery, I was working with WCS scientists in order to survey dozens of coral reef sites from Malindi to Shimoni, covering approximately 200km of Kenyan coastline. We saw delicate branching colonies of Porites and Pocillopora, the lettuce-like Pavona or brain-shaped Faviids, but generally the reefscape was dominated by those boulder-like Porites.