The Metridium Fields, one of my favorite divespots, is located off the Breakwater in Monterey. It's fairly long swim out (about 1000 feet I think) from the Breakwater beach, but definitely worth it. The easiest way to find it is to line yourself up with the small square pumphouse and swim directly away from it until you are almost even with the end of the Breakwater. Another reference point is Reeside Avenue which is the street than runs back from the pumphouse up a steep hill. The metridiums are arranged in clusters on rocks that run more less parallel to the shoreline.
Conditions are generally calm with very light surge. Depth ranges from about 50 to 70 feet. And Visibililty is usually in the 15-20 feet range. Beware of any passing boats as it is near the boat channel.
A note of thanks goes to Dan Clanon who introduced me to this spectacular dive.