Monterey’s Metridium Mountain

Although I dive the Monterey area quite a bit, I am constantly amazed how Monterey’s captains can find new and often better sites so close to our old favorites. This spring the Beachhopper II took me to such a site.
Metridium Mountain is located off of Stanford University’s Hopkins Marine Station. The anchorage is a short distance from the well-known site called Hopkins Deep Reef. At Hopkins Deep the rocks barely rise up off the bottom, while the rock structure is much more dramatic at Metridium Mountain.
The Metridium Mountain pinnacle sits on a relatively flat 65-foot bottom. Vertical rock walls jut straight up from all sides to form a rock structure that is reminiscent of the photogenic buttes of the American Southwest. The top is relatively flat and the sides are scored with deep cracks and crevices. A number of rockfish hide deep within the cracks along with dozens of rock scallops. These are in the look-but-don’t-touch category, since this site is within a reserve. The cracks are also home to orange sea cucumbers, and a horde of little shrimp. This is a relatively small site and you can easily swim around it several times during a dive.
The bottom around the pinnacle is flat, with a number of large boulders strewn about. There were a few small lingcod and rockfish, and a juvenile wolf eel was spotted near the anchor. This was a real treat since we normally encounter adult wolf eels in Monterey, and this one was out and about and not hiding in a crack. Wolf eels are not related to eels at all and are actually members of the Anarhichadidae family. They spend much of their time in dens that can be identified by the left over mollusk shells that accumulate on their front porch.
This site got its name for the pinnacle’s most conspicuous invertebrates — the white-plumed anemone or giant plumose anemone. The scientific name was once Metridium giganteum but was reclassified as Metridium farcimen about 15 years ago. These huge anemones cover the entire top of the rock and the north and east sides. This is the West Coast’s largest anemone; it can grow to around three feet tall with a stalk as large as five inches thick. These metridium have short fluffy tentacles that are nearly pure white, while their stalks are variable and can be white, cream, tan, brown, or orange. The small, fluffy-looking tentacles are used to feed on plankton. They also have long, slender fighting tentacles that are used to repel other anemones. This anemone is extremely long lived; one individual lived for nearly 100 years in an aquarium.
It seems that the populations of animals in Monterey’s reefs wax and wane with the seasons and in multi-year patterns. Late spring and summer is a great time to observe humpback whales as they feed in the rich Monterey waters. These are often observed as divers motor between dive sites, or while kayaking.
On the reef, sometimes there a number of nudibranchs, at other times none. Sometimes there are many tunicates; at other times the fish steal the show. Recently it was all about the gastropods. There were more snails than I have ever seen in one place. There were hundreds of hairy tritons, Kellet’s whelks, leafy hornmouths, and Ida’s miters. They were going about their snail business. Some were feeding, others were mating, and many were laying eggs.
This site is one of the calmest boat dives in Monterey and can be a comfortable experience for new divers even when the spring/summer northwesterly winds are blowing. It is a great place to photograph metridium anemones, and sometimes wolf eels. In summer you might get lucky and motor past a few humpback whales on your way to and from the site.
The author would like to thank Captain MaryJo Nelson and the crew of the Beachhopper II for their help in the preparation of this article.
At-A-Glance
Skill Level: Beginner or better
Location: Offshore of Hopkins Marine Station in Pacific Grove at 36° 37.327′ N, 121° 53.982′ W.
Access: Boats may be launched from the public ramps at Monterey Breakwater or between Fisherman’s Wharf and Wharf #2.
Facilities: None
Entry and Exit: Only boat access
Depth Range: 48 to 65 feet
Conditions: Predictably very calm
Visibility: 10 to 30 feet
Photography: Great macro photography even on days when the visibility to poor. Great wide-angle photography of anemones when the visibility is better.
Hunting: None, this site is within the Lovers Point-Julia Platt State Marine Reserve.
Cautions: Watch for thick kelp, surge, and boat traffic
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