Luis Javier Sandoval's Image

The beaches of the Yucatan Peninsula, Mexico, near Cancún are traditional nesting sites for the endangered green turtle.

But as Cancún has also grown as a holiday and dive resort, development has reduced the area available to turtles. Today, though, many nest sites are protected, there are turtle hatcheries to help numbers increase, and there is publicity to help local people and resort owners value the natural riches of the region. Luis earns enough from tourism photography to allow him time to document his beloved wildlife. 'The turtles are so used to seeing people in the water that they think we're just part of the environment,' says Luis, which means he has been able to get to know individuals, recognising them from the markings on their faces. 'This metre-long female, grazing on seagrass, took no notice of me, apart from glancing up briefly.' Recently, Luis has noticed what he suspects may be a new threat: at certain times of the year, a yellowish alga covers some of the seagrass. The suspicion is that the algal growth is the result of sewage from the resort, which has already affected the coral. What is clear is that the turtles avoid eating it.