The turtles were fitted with special tiny swimming suits and put in tanks to see how they reacted to magnetic fields.
They found out the turtles used an internal 'compass' which recognises changes in the Earth's magnetic field and so points them in the right direction.
When they start their amazing journey which can take up to 10 years, they're about five centimetres long and defenceless.
Even as they hatch, they're in danger of being eaten by ghost crabs, raccoons, skunks, foxes, or dogs. In the oceans, they face sea birds, crabs, and carnivorous fishes.
They make the dangerous and long migration swim across the oceans to escape being eaten.