The metal tag on Castello, a male sea turtle that had been “tagged” in Greece, showed that over a span of 10 years he completed a journey of thousands of kilometers from one end of the Mediterranean to the other.

“Archelon,” the Sea Turtle Rescue Centre, described Castello’s story in a post. The turtle had received treatment at the Rescue Center in 2014 after suffering a serious head injury. Following a long rehabilitation period, he was released back into the sea in good health in 2015.

He was carrying a tag with his identification details.

In December 2025, Castello was spotted in the Balearic Sea and transferred for treatment to a rehabilitation center in Barcelona. The turtle had a fishing hook in its mouth, as well as an old, healed wound on its lower jaw.

Spanish specialists found the metal tags from “Archelon” and contacted their Greek counterparts.

Castello’s journey from Greece to Spain—a straight-line distance of more than 1,500 kilometers—shows that sea turtles are capable of surviving and undertaking long-distance journeys across the Mediterranean.