There are several theories as to how sea turtles are able to the same beach to nest, but none have yet been proven. The most common theories are:
- They can detect both the angle and intensity of the earth’s magnetic field. Using these two characteristics, a sea turtle may be able to determine its latitude and longitude, enabling it to navigate virtually anywhere. Early experiments seem to show that sea turtles have the ability to detect magnetic fields. Whether they actually use this ability to navigate is the next idea being investigated.
- It is believed that hatchlings imprint the unique qualities of their natal beach while still in the nest and/or during their trip from the nest to the sea. Beach characteristics used may include smell, low-frequency sound, magnetic fields, the characteristics of seasonal offshore currents and celestial cues.
- Younger female turtles may follow older, experienced nesting turtles from their feeding grounds to the breeding site.
- Lohmann KJ and Lohmann CMF 1992. Orientation to oceanic waves by green turtle hatchlings. Journal of Experimental Biology 171: 1-13.
- Lohmann KJ, Lohmann CMF, Ehrhart LM, Bagley DA and Swimg T 2004. Geomagnetic map used in sea-turtle navigation. Nature 428: 909-910.