Cooper Reef is a submerged rocky reef out in the open just North of the HMCS MacKenzie artificial reef wreck and South of Arachne Reef. Those 2 sites are covered with current-loving invertebrate life so it's reasonable to assume that Cooper Reef, which is between them in the same body of water and exposed to the same currents, should have similar invertebrate life. I came here on a SEA Dive charter on Sept. 5, 2022.
According to the marine chart, the steepest/deepest area seemed to be along the North side of the reef. My plan was to swim down this North slope and then follow it around West through the channel between the main reef and another one next to it. The idea was that the current might be forced to accelerate through the channel, creating an area with more current-type invertebrate life. Visibility wasn't great, but not terrible. Maybe 15'. The rock slope wasn't as steep as I expected. At first it seemed pretty bare. As we went deeper, the bottom was covered with orange burrowing cucumbers. In the Winter these cucumbers go dormant and retract their tentacles so the bottom would seem much less colourful then.
I reached the bottom of the rocky slope about 60' deep. Here, there was a flat plain of sand, shells and small rocks. I swam out for a bit to see if the rocky slope would start up again, but I didn't swim out too far since I didn't want to waste time out in an uninteresting area. I think I gave up too soon since the sidescan image seems to show another rocky area starting up out there that goes down deeper.
I swam back to the base of the rocky slope and continued swimming West towards the channel. There were several copper, quillback and brown rockfish along the slope. This is part of a Rockfish Conservation Area so hook-and-line fishing and spearfishing are illegal. Of course, since this is a RCA, there were a few boats in the area fishing. The farther west I swam, there seemed to an increasing amount and variety of invertebrate life. There were lots of swimming scallops, red burrowing cucumbers, feather-type hydroids and some areas with giant barnacles and grey gnarled sponge. On thing I found strange was the lack of plumose anemones. I don't know why I judge the quality of dives in this area by the amount of plumose anemones. Usually, I find that when there are lots of plumose anemones, the current is strong enough in the area to support lots of other colourful invertebrates as well. Areas without plumose anemones just seem more empty to me as well. Anyway, here there were none at all. The slope of orange cucumbers along with all the other tiny, colourful invertebrates should have been interesting enough, but I found that as I drifted along, it all started to look the same to me.
I don't know when I finally entered the channel between the main reefs. There didn't seem to be an obvious corner, but eventually I noticed that my compass heading was trending in the direction of the channel. Earlier, my maximum depth along the rocky slope was about 80' deep. I'm guessing that was in the area of the "corner" where the slope curves around into the channel. Here in the channel, the sandy bottom was 70' deep. There were a few boulders out on the sand. When I swam out over the sand slightly, I could just see another rocky slope starting up in the distance. I assume this was the start of the adjacent reef, but I didn't look too closely. I stayed along the rocky slope of the Eastern reef. The marine life here seemed to be the same as I had seen throughout the rest of the dive. There were still no beds of plumose anemones.
I started the swim up the slope into the shallows near the top of the reef.
I think this dive was ok, but nothing special compared to nearby Arachne Reef and HMCS MacKenzie. I think the best area was around the "corner" where the North side of the reef turns into the channel. I'm not saying I wouldn't dive here again, but if I did, I might try the Eastern side of the reef which might catch more of the current flowing down Boundary Pass.