Green Sea Turtle
The most well known sea turtle, green sea turtles are the commonly seen off Orange County although still pretty rare. Many of the local sightings seem to happen around the local beaches and in the harbors. There is also several green sea turtles that hang out in the San Gabriel River in Long Beach near the power plants where there is warm water being discharged.
If you see one, take photos and submit your sighting to So Cal Sea Turtles