Loggerhead sea turtles (Caretta caretta) have one of the most interesting developmental migrations of all marine turtles. Pacific loggerheads hatch on nesting beaches in Japan. When they are just 3.5 cm long, they leave the beaches of Japan and swim across the Pacific Ocean to the west coast of North America where they live for an unknown number of years. When these turtles finally arrive back in Japan, they've grown to about 40 cm in length. Once in Japan, the turtles lay eggs on the same beaches where they were themselves hatched. In recent years, researchers have attempted to identify and even track individual Pacific loggerhead turtles found off the West coast of North America swimming to Japan.

In 1998, two loggerhead sea turtles were released from San Diego, California, after an extended residency at SeaWorld San Diego. Both turtles headed immediately for Japan. Unfortunately neither of these turtles made it all the way to Japan before the batteries in their transmitters expired, but it is clear that this was their destination. Both turtles appeared to be guided on their journey by the temperature of the water. The pathways both turtles chose stayed very close to the part of the Pacific Ocean where the surface temperature of the water was about 19° Celsius. The fact that loggerheads can follow the water temperature or "thermal band" all the way across the Pacific and reach Japan may partially explain how the turtles find their way across the ocean to their nesting sites. However, it is still too early to draw this conclusion. The maps made from satillite information seem to show the turtles following the water temperature; but the readings may not be detailed enough to make a conclusion. The next step is to attach satillite transmitters with temperature sensors onto turtles being released into the Pacific. With this, Dr. Eckert hopes to directly measure the water temperature where the turtles are swimming, as the turtles make their way across the ocean to Japan.