Green Sea Turtle
The largest of the hard shell turtles, green sea turtles are not commonly sighted here in Orange County but they are definitely around. While they do not lay their eggs in California, they can be seen when they come up for air in the ocean or in the harbors. There are sightings of green sea turtles several times each year in Dana Point Harbor, Newport Harbor, Newport Back Bay, Bolsa Chica Wetlands, and randomly in the ocean. Since they can hold their breath up to 5 hours, you just don't see them at the surface often.
The best place to actually see one around here is in the San Gabriel River where there are lots of them. While this seems like a very strange place because the 2 mile stretch of river from the ocean to the cement section is very green and filled with trash, the water is warm and has food for them. If you walk along the San Gabriel River Trail and look down at the water, you'll likely sea turtles pop up randomly.
If you see one, take photos and submit your sighting to So Cal Sea Turtles
Green sea turtles are the largest hard shelled turtles in the world, reaching up to about 400 lbs. and 5 ft. in length although they have been documented at double that weight in rare cases. The green sea turtles we see here off California likely come from Mexico although some might come all the way from Hawaii as well.