Metridium fields have become our default dive for San Carlos Beach/Breakwater. We've found that the worse the visibility, the more Metridium are out. Find the large pipe just north of the bathrooms and pump house. There are several small pipes that could mislead you. The big one is probably 2+ feet in diameter. Once you've found the pipe follow it out until its end. Then, take a heading directly at magnetic north and you should reach the metridium within 50-100 feet. We've seen lots of sea-life along the pipe... many rockfish, halibut (some several feet long), seals, otters, many nudibranchs.