The temperature of the sand where sea turtle eggs incubate determines whether the hatchlings are male or female.

Sea Turtle Day highlights some of the ocean's most ancient mariners—reptiles that have existed for over 100 million years. Observed each year on 16 June, it raises awareness of their ecological importance and the growing threats they face. Sea turtles play a vital role in maintaining healthy seagrass beds and coral reefs, ecosystems that support diverse marine life. Long migrations between feeding and nesting areas are central to their life cycle. Despite their resilience, all species are threatened by habitat loss, plastic pollution, climate change and accidental capture in fishing gear.

Pictured here near the Cayman Islands, a pair of hawksbill sea turtles glide through clear Caribbean waters. Known for their patterned shells and narrow, hawk-like beaks, hawksbills help maintain reef balance by feeding mainly on sponges, which prevents them from overtaking corals. Critically endangered, they are among the rarest sea turtle species—making encounters like this even more remarkable.