A team of scientists from Australia, Britain and the US used satellite tracking to reveal that the turtle can travel up to 4,000 kilometres without stopping for food.
The study has raised questions about whether marine parks can protect wide-roaming species.
Reporter: Tom Maddocks
Speaker: Dr Daniel Ierodiaconou, School of Life and Environmental Sciences, Deakin University, Warrnambool
MADDOCKS: Four-thousand kilometres is a long way to swim without stopping for food.
It's a trip similar sized mammals like dolphins or seals wouldn't be able to make without starving to death.
To find out where, why and how the journey was achieved, a team of scientists attached GPS tracking equipment to the backs of eight green sea turtles.
IERODIACONOU: We observed Green Turtles making migrations that have never been recorded in the scientific literature before, so up to four-thousand kilometres, so they were moving from in the middle of the Indian Ocean to the coasts of Africa.
MADDOCKS: Deakin University's Dr Daniel Ierodiaconou was one of the team monitoring the turtle's movements.
He and his colleagues were able to track very fine-scale movement for more than two years.
On the long migration, the turtles had to rely on their fat reserves.
Green sea turtles are vegetarians, and were comfortably feeding on the sea grass and seaweed that sits in the shallow coastal waters of the Chagos Islands, an isolated group of islands in the middle of the Indian Ocean.
So why did they move away from their habitat?
IERODIACONOU: We think it has something to do when they're juveniles, so when these turtles were born and they left these grounds, they were drifting along in currents and if you look at where Chagos is and if you actually do some modelling with current movements and buoys that we have available, you can see that they sort of spread out all across the Indian Ocean. So what we believe is that these turtles are actually going back to foraging grounds that they've actually been passively pushed towards by these currents and returning back to their home grounds to nest.
MADDOCKS: The study found that the turtles roamed far beyond the borders of the large marine protected zones.
In the 64,000 square kilometres of protected area, only one of the eight turtles remained in the marine park for the entire time.
Dr Ierodiaconou says while protection zones serve a purpose, they're artificial.
And he says marine parks need to be organised as a world network, with regional organisations working together.
IERODIACONOU: What this study really highlights is that if we have big marine parks and we can compliment them by little marine parks, in this case, to protect small areas of foraging, you're actually protecting much of the life history of these animals. So them travelling those four-thousand kilometres, while it sounds like a lot, it's not actually a lot of their time in their life history. So if you can protect the small patches of where they're foraging, with the areas where they're nesting, your protecting 90-percent of their actual life history time.
MADDOCKS: He says technology is revolutionising data collection.
And it's technology which is imperative to developing a network of smaller protected areas across vast expanses of ocean.
IERODIACONOU: I think the world's management agencies are becoming more spacially aware. It's possible for us to go out in the field for a couple of weeks and collect data over years, so these turtles are pinging information to satellites for years and as this data keep building, we're going to have a better understanding of where these biodiversity hot spots are and we'll be able to make better informed decisions as an international community and that's really the goal. What's the best sort of outcomes to enhance the biodiversity and protect the biodiversity that we have.