The majestic sea turtle is undoubtedly one of the most universally beloved and sought-after marine encounters for scuba divers traversing the world's oceans. Belonging to the ancient superfamily Chelonioidea, these remarkable marine reptiles have graced our oceans for well over 100 million years, sharing the prehistoric seas with the dinosaurs before surviving the great extinction events that shaped modern biodiversity. Today, seven distinct species navigate the globe, with scuba divers most frequently crossing paths with five of them: the green, hawksbill, loggerhead, olive ridley, and occasionally the colossal leatherback turtle. Adapted beautifully to an aquatic existence, sea turtles feature streamlined, hydrodynamic shells and large, paddle-like flippers that allow them to glide effortlessly through the water, transforming them from clumsy terrestrial wanderers into the elegant aviators of the underwater realm.
Behaviour & reproduction
- Size
- 0.6-1.5 metres (shell length)
- Weight
- 40 kg to 700 kg (Leatherbacks being the heaviest)
- Lifespan
- 50 to 100 years, with some individuals likely exceeding a century
- Status
- Critically Endangered (Hawksbill), Endangered (Green)
Slightly less common on standard tropical reef dives, but equally magnificent, is the loggerhead turtle. Named for its exceptionally large head and massively powerful jaw muscles, the loggerhead is built for crushing heavily armoured prey. Their diet consists largely of benthic invertebrates, including thick-shelled conchs, bivalves, and formidable crabs, making them vital regulators of the ocean floor community. Meanwhile, the olive ridley turtle, while mostly renowned for its spectacular synchronised mass nesting events known as 'arribadas', spends the vast majority of its life foraging in the pelagic zone. The undisputed giant of this ancient lineage is the leatherback turtle. Unlike its hard-shelled relatives, the leatherback possesses a flexible, rubbery carapace composed of tough, oil-saturated connective tissue. This extraordinary adaptation allows the leatherback to withstand the immense hydrostatic pressures of extreme depths as it dives thousands of metres into the freezing abyss in pursuit of its exclusive diet of jellyfish.
