The Caribbean's Mesoamerican Reef is the second largest barrier reef in the world, stretching 600 miles (965 km). Only the Great Barrier Reef surpasses it.
The reef's northernmost point aligns with Cancún in Mexico. From there it stretches south-east alongside the coasts of Mexico, Belize, Guatemala and Honduras.
Visitors flock to its sandy-white beaches and warm seas to snorkel and scuba dive. The Mesoamerican Reef supports millions of people along the neighbouring coasts.
But the tourism industry, combined with ecological pressures like overfishing and pollution, are taking their toll on the reef and the many local fishing communities.
This summer, the International League of Conservation Photographers partnered with Comunidad y Biodiversidad (COBI) to encourage sustainable practices, such as no-take fish refuges that allow populations to recover. They want 20% of the reef protected as a no-take zone.
Some fishermen are now trying to be more sustainable. South of Cancún in the Sian Ka'an biosphere reserve, the Punta Herrero commercial fishing cooperative consists almost entirely of men fishing for Caribbean Spiny Lobster.
The fishermen free-dive for lobsters, using small concrete hutches to attract and shelter the lobsters so they can be harvested by hand. This method decreases the amount of by-catch and reduces the impact to the reef.
However, in the much-visited Riviera Maya there is a large demand for fancy lobster dinners, including out of season when lobster fishing is not sustainable. Campaigners are now trying to persuade tourists to insist on sustainably-caught lobster.
South of Cancún at Akumal, sea turtles graze on seagrass in the clear blue water.
Seagrass also serves as a nursery for many coral reef fish – some of which are eaten by sea birds. Akumal's tourism industry depends on the health of the seagrass, so there are strict regulations on snorkeling.
The Limones site in the Puerto Morelos Reef National Park is now closed to everyone, including tourists and fishermen. As a result, the once-diseased elkhorn corals (Acropora palmata) are healthy, and are once again sheltering organisms like snappers, grunts and lobsters.