The society wants marine sanctuaries to protect sea turtles in Australian waters.

The 10-metre sand turtle took about two hours to construct and was a collective effort aimed at raising awareness on the eve of World Turtle Day.

Nicola Bowskill, from the Wilderness Society Newcastle, said turtle sand sculptures were also carved on beaches in Perth, Broome, Darwin and Caloundra yesterday.

Six of the world's seven species of sea turtle can be found in Australian waters and all are listed as vulnerable or endangered.

Fishing nets cut adrift in the ocean could entangle turtles, causing them to drown, while warming temperatures also posed threats to turtle populations, Ms Bowskill said.

- Martin Dineen