Oceans contain about 70 per cent of the Earth’s water and about 500 dead zones that are more than 245,000 square kilometres in size, according to UNESCO. That’s the equivalent of the surface of the United Kingdom. And it’s only getting worse, with climate change eroding ecosystems and man-made intrusions such as plastic causing underwater catastrophes. | Above: Fiji, which will use the Expo 2020 platform to showcase marine conservation