Marine life

Green Turtle

Chelonia mydas

The most commonly encountered turtle on Australian reefs, and a reliable sight at Cook Island and the southern Great Barrier Reef.

Green turtles are the turtle most Australian divers meet, and on the southern Great Barrier Reef cays and at sites like Cook Island they are close to guaranteed.

Adults are herbivorous, grazing on seagrass and algae, which is unusual among sea turtles and is where the name comes from — the green refers to the colour of the body fat, not the shell.

They rest under ledges and on the reef, and a resting turtle will often tolerate a diver at very close range provided nobody blocks its route to the surface.

A green sea turtle encounter, represented by an AI-generated editorial image.

Scientific name	Chelonia mydas
Typical size	Shell commonly 80–120 cm
Conservation status	Endangered
Peak months	October, November, December
Documented sites	9
States	Queensland, New South Wales, Western Australia

When to see them

possible good peak

Present year-round. Nesting on Great Barrier Reef cays runs roughly November to March, with hatchlings emerging from January.

Where they are

Documented sites for Green Turtle. Hover a marker for the site name.

Identification

single pair of scales between the eyes
smooth, rounded shell, olive to brown with darker mottling
blunt, serrated beak suited to grazing
smaller head relative to body than a loggerhead

Behaviour

Adults graze seagrass and algae; juveniles are more omnivorous.
Rests under ledges and overhangs, often for extended periods.
Nests on sandy cays and beaches, returning to natal beaches to breed.

In-water etiquette

Green Turtle is endangered. How divers behave around it genuinely matters.

Never block a turtle's path to the surface — they are air breathers and this is genuinely stressful.
Do not touch, ride or chase.
Keep clear of resting animals under ledges; give them an exit.
On nesting beaches, follow local rules on lights and distance.

Where to see them

Sites where this species is documented as a reliable encounter.

Cook IslandAn aquatic reserve off Tweed Heads with a resident turtle population and seasonal grey nurse sharks.Heron IslandA research-station coral cay with the Heron Bommie a few minutes from the jetty.Lady Elliot IslandA coral cay at the reef's southern tip, with some of Australia's most reliable manta encounters.Lady Musgrave IslandA coral cay enclosing a navigable lagoon — sheltered diving with excellent clarity.Flat RockSoutheast Queensland's premier big-animal site — grey nurse sharks, mantas and turtles.Julian Rocks (Nguthungulli)Where tropical and temperate waters meet — more than 20 shark and ray species recorded.Ningaloo ReefA fringing reef close enough to shore that in places you can swim to it from the beach.Great Barrier Reef (Cairns Outer Reefs)The reef systems reached daily from Cairns — the most-dived section of the Great Barrier Reef.Tangalooma WrecksFifteen deliberately scuttled vessels in shallow, sheltered water off Moreton Island.

Operators servicing those sites

Businesses documented as diving the sites above. Confirm seasonality and requirements directly.

Gold Coast Dive CentreA Gold Coast training and service business serving local divers and visitors.Gold Coast Dive AdventuresA Gold Coast operation focused on guided local diving and charter access to offshore sites.Heron Island ResortA coral cay resort on the southern Great Barrier Reef with an on-island dive operation and sites a short boat ride from the jetty.Lady Elliot Island Eco ResortA coral cay resort at the southern tip of the Great Barrier Reef, strongly associated with manta ray encounters and accessed by light aircraft.Lady Musgrave ExperienceA Bundaberg-based operation providing day and overnight access to Lady Musgrave Island and its lagoon.1770 ReefAn operation running trips from the Town of 1770 to Lady Musgrave Island and the southern Great Barrier Reef.Manta Lodge & Scuba CentreA North Stradbroke Island operation combining accommodation and diving, which makes it structurally different from a suburban Brisbane training centre.Sundive Byron BayA Byron Bay operation running daily Julian Rocks diving alongside introductory scuba and recreational training.Byron Bay Dive CentreA Byron Bay operation providing Julian Rocks diving and recreational training.Exmouth Dive & Whalesharks NingalooAn Exmouth operation running certified scuba diving alongside whale shark and other wildlife tours. The scuba and snorkelling products are distinct and should be booked deliberately.Ningaloo Reef DiveA Ningaloo operation based at Coral Bay providing reef diving and training.Dive NingalooAn Exmouth operation focused on certified scuba diving, including Navy Pier access.

Often seen on the same dives

Grey Nurse SharkAustralia's most recognisable dive shark — ragged teeth, entirely harmless, and critically endangered on the east coast.Humpback WhaleHeard far more often than seen — the soundtrack to winter diving on both Australian coasts.Leopard Shark (Zebra Shark)A docile, spotted bottom-resting shark that arrives on the east coast with summer's warm water.Loggerhead TurtleHeavier-headed and less common than the green turtle, with a nationally significant nesting population near Bundaberg.Manta RayReef mantas at cleaning stations — Lady Elliot and Ningaloo are the most reliable encounters in Australia.Queensland GroperThe largest reef-dwelling bony fish in the world, and a defining feature of the SS Yongala.

Frequently asked questions

Where is the best place to dive with turtles in Australia?

Cook Island off Tweed Heads and the southern Great Barrier Reef cays — Heron, Lady Elliot and Lady Musgrave — are the most reliable.

When do turtles nest on the Great Barrier Reef?

Roughly November to March, with hatchlings emerging from around January.

Last researched: September 2026. Dive businesses change frequently — confirm current services, prices and requirements directly with the operator before booking.