Doug saw this Leatherback Turtle (Dermochelys coriacea) off Kehoe Beach at Point Reyes on 16 August 2015.
Here's another great shot of the turtle with Kehoe Beach in the background:
Leatherbacks are the largest living turtles. They reach lengths of ~6.5 feet (2 meters) and weights of up to ~1,400 lbs. (650 kg).
Turtles feeding in this area during the summer may nest in the western Pacific (e.g., Indonesia, Papua New Guinea, the Solomon Islands). It's about a 6,000 mile (9,700 km) swim across the Pacific Ocean.
One of the Leatherback's primary prey is jellyfish. They feed on them at the surface, but they can also dive as deep as 4,200 ft. (1,280 meters) and stay under water for as long as 70 minutes!
For more information about Leatherbacks, check out NOAA's web page here.
And again, many thanks to Doug for taking the time to observe and document this turtle and for sharing the pictures with all of us.