INCREDIBLE footage has emerged showing thousands of green sea turtles converging on the Great Barrier Reef for their annual nesting migration.

The footage, shot by photographer Christian Miller, shows scores of turtles floating near Raine Island, a vegetated coral cay on the outer Great Barrier Reef and home to the largest Green Turtle nesting ground in the world.

About 70 per cent of the world's green turtle population nest in the remote locale.

A green sea turtle on the Great Barrier Reef.
A green sea turtle on the Great Barrier Reef.

Mr Miller said it was a special experience to witness.

"During the day they are just hanging and relaxing near their preferred nesting beach," he said.

"When dawn breaks in most of them will start heading towards the beach for a long and exhausting process getting up above the tide line, digging a deep hole to eventually lay over 100 eggs."

Turtle watching has become a significant niche for the tourism industry, with thousands of people descending on Mon Repos near Bundaberg every summer to witness the nesting and hatching of turtles.