Green sea turtles venture into the open ocean immediately after hatching on the Florida coast, and then seem to vanish for a spell — now, new tracking data shows that, after surfing the Gulf Stream northward, many turtles drop out of the current to enter the Sargasso Sea, an oasis of cozy seaweed and plentiful food.

In the new study, published Tuesday (May 4) in the journal Proceedings of the Royal Society B, scientists attached solar-powered satellite tags to 21 green sea turtles (Chelonia mydas) of “toddler” age, meaning about 3 to 9 months old. The young turtles weighed just over 10.5 ounces (300 grams) and their shells measured about 5 to 7 inches (12 to 18.6 centimeters) long; tagging such small creatures presented a huge challenge, both due to their initial size and the fact that they grow and change shape fairly rapidly, compared with mature animals.