Green sea turtles are the most common sea turtles, and can be found in warm waters. They have been spotted in tropical waters around 139 different countries. Their body shape and paddle-shaped flippers make them excellent swimmers. They have been known to swim over 1,400 miles (2,253 km) from their feeding ground to their nesting site! They also have good memory; when the time comes to build their nests and lay their eggs, they return to the same sandy beach where they were born. No one knows how long they live, but people think they can live to be around 100 years old!