Cottam Reef - Pacific Northwest
Cottam Reef is a solid pick for a Pacific Northwest dive, offering a good glimpse into what makes these colder waters special. You're descending onto a reef that’s more about the texture and character of the rock than sprawling coral, but it’s absolutely packed with anemones, sponges, and the occasional grumpy lingcod tucked into a crevice. We often find giant pacific octopuses here too, sometimes just their eyes peering out from under a rock. Visibility can be a bit of a gamble, as with most PNW sites, but when it's good, Cottam delivers a genuinely engaging dive for those who appreciate the subtle beauty of temperate reefs.
- Location
- Pacific Northwest, United States, North America
- Coordinates
- 49.316330, -124.186040
- Type
- reef
Best Time to Dive in Pacific Northwest
The warmest water temperatures in Pacific Northwest occur in August, averaging 16.5°C (up to 15.6°C). The coolest conditions are in February at 6.9°C.
Monthly Water Temperatures
- January: 7.1°C (air: 6.3°C)
- February: 6.9°C (air: 4.5°C)
- March: 7.7°C (air: 6.6°C)
- April: 9.5°C (air: 8.7°C)
- May: 12.0°C (air: 11.7°C)
- June: 14.0°C (air: 13.7°C)
- July: 15.7°C (air: 14.9°C)
- August: 16.5°C (air: 15.7°C)
- September: 14.3°C (air: 14.0°C)
- October: 11.4°C (air: 10.5°C)
- November: 8.8°C (air: 7.4°C)
- December: 7.7°C (air: 5.5°C)
Nearby Dive Sites in Pacific Northwest
- 100 Foot Rock
- Alki Beach Park
- Alki beach Seattle ferry north
- Am/Pm Beach - 13m (shore)
- Ansell Point Dive Site - 5-20m (shore)
- Arachne Reef - 5-20m (reef)
- Arachne Reef (reef)
- Arbutus Island - 10-30m (shore)
- Arbutus Point - 23m
- Atkins Reef (reef)
- Atrevida Reef (reef)
- Barnard Castle - 15-35m (pinnacle)
- Bell Island
- Blake Island Reef (reef)
- Blind Reef (reef)
Nearest Dive Centres to Cottam Reef
Marine Life in Pacific Northwest
Home to 38 recorded species including 18 reef fish, 7 crabs & lobsters, 3 whales & dolphins, 2 sharks & rays, 2 clams & mussels, 2 sea urchins.
Notable Species
- Pacific herring (Clupea pallasii) - Reef Fish
- coho salmon (Oncorhynchus kisutch) - Reef Fish
- Spiny Dogfish (Squalus suckleyi) - Sharks & Rays
- Chinook (Oncorhynchus tshawytscha) - Reef Fish
- Dungeness Crab (Metacarcinus magister) - Crabs & Lobsters
- Common shore crab (Carcinus maenas) - Crabs & Lobsters
- red salmon (Oncorhynchus nerka) - Reef Fish
- California Spot Prawn (Pandalus platyceros) - Crabs & Lobsters
- Slender Crab (Metacarcinus gracilis) - Crabs & Lobsters
- Rainbow Trout (Oncorhynchus mykiss) - Reef Fish
- Whiting (Merluccius productus) - Reef Fish
- Pacific krill (Euphausia pacifica) - Crabs & Lobsters
- Common Seal (Phoca vitulina) - Whales & Dolphins
- Eulachon (Thaleichthys pacificus) - Reef Fish
- Red Rock Crab (Cancer productus) - Crabs & Lobsters
- Spotted Ratfish (Hydrolagus colliei)
- Calico salmon (Oncorhynchus keta) - Reef Fish
- Slender Sole (Lyopsetta exilis) - Reef Fish
- Pacific Geoduck (Panopea generosa) - Clams & Mussels
- Olympia oyster (Ostrea lurida) - Clams & Mussels
Recommended Packing List for Cottam Reef
Based on average water temperature of 11.0°C, currents 7 cm/s.
- Wetsuit (5-7mm) - recommended for 11°C water
- Hood & Gloves (3-5mm) - helps retain warmth
- Mask - essential for every dive
- Fins
- BCD - buoyancy compensator
- Regulator - your most safety-critical piece of gear
- Dive Computer - tracks depth, time, and NDL
- Surface Marker Buoy (SMB) - essential for boat pickups
- Dive Torch - useful for crevices and colour at depth
- Underwater Camera - capture your diving memories