Aerial view of a boat working in the green water of Taihu Lake covered by blue-green algae, Wuxi city, Jiangsu province, China on May 23, 2018. (Photo by Imaginechina/Rex Features/Shutterstock)

Tourists play at a beach covered by a thick layer of green algae on July 3, 2013 in Qingdao, China. A large quantity of non-poisonous green seaweed, enteromorpha prolifera, hit the Qingdao coast in recent days. More than 20,000 tons of such seaweed has been removed from the city's beaches. (Photo by China Foto Press)

Tourists play at a beach covered by a thick layer of green algae in Qingdao, China, on July 3, 2013. A large quantity of non-poisonous green seaweed, enteromorpha prolifera, hit China's Qingdao coast last month. More than 20,000 tons of such seaweed has been removed from the city's beaches. This has now become an annual summer event. (Photo by Whitehotpix/ZumaPress.com)

Visitors take photos of the fluorescent sea in the waters of Paishi Village, Dalian City, Liaoning Province, China, May 24, 2020, from the night of May 24 to the early morning of May 25, 2020. The fluorescent sea in dalian is caused by noctilucent algae in the sea water. (Photo by Costfoto/Barcroft Media via Getty Images)

Fishermen are surrounded by green water as they use large nets to catch fish. The workers were pictured trying to find fish below the algae in Rajshahi, Bangladesh in the last decade of February 2024. (Photo by Bipul Ahmed/Solent News & Photo Agency)

A father and son spend all day fishing in Naogaon, northern Bangladesh in the first decade of December 2024, before heading to market to sell their 3kg catch for the equivalent of a few pounds. The vibrant green algae makes conditions difficult but that does not deter them. (Photo by Estiak Ahmed Munna/Solent News)

Growing cities, overuse of fertilizers and factory wastewater have degraded China's water supplies to the extent that half the nation's rivers and lakes are severely polluted. China aims to spend $850 billion to improve filthy water supplies over the next decade, but even such huge outlays may do little to reverse damage caused by decades of pollution and overuse in Beijing's push for rapid economic growth. Photo: Fishermen row a boat in the algae-filled Chaohu Lake in Hefei, Anhui province, June 19, 2009. (Photo by Jianan Yu/Reuters)

Teeming with images of spectacular underwater scenes from around the world, Call of the Blue is the culmination of a five-year project by the photographer and ocean conservationist Philip Hamilton. This groundbreaking book includes contributions from acclaimed scientists and ocean “guardians”, who reveal what drove them to answer the call of the blue. (Photo by Philip Hamilton/The Guardian)