Schelt inlet is full of them.
Closer to Vancouver you can find them at most of the sites with rocky bottoms on the open ocean side. I've never seen them at Porteau or Whytecliff or in Burrard Inlet or places where a lot of divers go. They're just too shy to put up with a lot of company. If you have to bushwhack your way to the entry point (or take a boat) then you'll have better luck finding octopus.
Spotting them is a real challenge, though. Scan the landscape and look for shells, like crab shells for example. If you see a lot of them in a small area then there's a good chance that an octopus lives near by. Once you think you're close, look under the rocks (don't lift stuff up, just use your light and your eyes or you may harm the animals). Also look for details. They can be pretty big but usually you spot them by seeing the tip of an arm or some little detail. They can also fit into surprisingly small spaces so think small... And keep trying. The fact is you can't find octopus on command. Sometimes you'll go for dozens of dives without spotting one.
R..