[Photo] A green sea turtle eyes the camera. CREDIT: Dr. Robert Schroeder, NOAA/NMFS/PISC/JIMAR/CRED.

Sea turtles are known for the amazing migrations they make, swimming long ocean distances to return to their birthplace to hatch their young.

Yet it turns out these beloved marine reptiles make another migration earlier in life that one researcher has described as "even more amazing" than the migrations the turtles make as adults.

"They only do it one time, but [the migration] can be much longer than the reproductive migrations they do as adults, and may involve tens of thousands of kilometers," said Peter Meylan, a professor of natural sciences at Eckerd College in St. Petersburg, Fla., in a statement.

Meylan, along with his research partner and wife Ann Meylan, of the Florida Fish and Wildlife Research Institute, recently summarized years of sea turtle tracking data in a paper published in the Bulletin of the American Museum of Natural History.

They found that young sea turtles travel extremely long distances before they're fully grown.

Green turtles hatched in Costa Rica were tracked to far-flung spots — Barbados, North Carolina and Bermuda — before heading off to spend their adulthoods near Nicaragua.

"Bermuda is a place where young turtles go to grow up," Meylan said. "They arrive there after living out in the ocean. In Bermuda waters they grow from about the size of a dinner plate to the size of a wash tub, and then move on to different, adult habitats," he said.

The researchers concluded that the tagging data from the study suggest that these adolescent migrations can be a dangerous time for the young turtles, and that the ocean corridors they travel could need official protections.

Some ocean turtle species, such as the world's largest turtle, the colossal leatherback, are critically endangered.