Monterey California Snorkeling
I originally come from the Monterey Bay area, in central California. Out of curiosity I read your section on snorkeling in California. I have been snorkeling several times in Monterey. On a nice day, the water is not nearly as cloudy as it looks once you're in the water away from the shore. The nutrients in the cold water allow for more diversity among species, although they can be hard to spot in the amazing giant kelp.
A thick wetsuit is definitely a must (6mm in my experience), as well as a hood and gloves. There are many excellent dive shops along Cannery Row, and the Monterey Bay Aquarium is nearby and a must-see for any ocean lover.
Hope this helps! :) Happy travels!! (I was just reading your recommendations for snorkeling spots on Kaua'i while I am there for a week.)