When baby sea turtles wriggle out of their sandy nests on Atlantic beaches, they enact an age-old ritual and head for the open sea.

Then what?

Scientists have never been sure. They know that after a few decades, sea turtles reach adulthood and return to the Atlantic coast.

But the specifics of their journey — dubbed their “lost years” — have been unclear.

Now, a study published in the journal Proceedings of the Royal Society B explains where at least some sea turtles head after hatching: the Sargasso Sea.

This contradicts previous theories that turtles simply drifted along on ocean currents until they reached adulthood. Scientists at the University of Central Florida attached tiny solar-powered tracking devices to 21 green sea turtles’ shells, then tracked them for 152 days. Fourteen of the turtles headed to the Sargasso Sea, a body of water defined not by land boundaries but by North Atlantic currents.

The researchers had done the same experiment with loggerhead turtles in a previous study; in that study, seven of 17 turtles went to the Sargasso.

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“Enough turtles made this journey that it really throws into question our long-held beliefs about the early lives of sea turtles,” said Kate Mansfield, a UCF associate professor of biology who led the research, in a news release.

Researchers plan to untangle the why behind the migration — and push for conservation efforts in the Sargasso.

The sea is named for a type of brown seaweed called sargassum. Researchers say it provides protection from predators, a rich food supply and warmth that promotes growth. But they want to know more about how sea turtles interact with Sargassum and whether the turtles orient toward the seaweed or the sea itself.