Besides the great information above, I also recommend you consult a tides chart before making plans ... you want to be here on a week when tides are reasonable. For example, this particular week would not be a good time to be here, as we're seeing some 13-14 foot tidal exchanges. That creates a lot of current, and tends to make the best dive sites undiveable.
Choose a week when tides are smaller ... in the 2-6 foot range, preferably ... that will allow you access to some of the better dive sites.
I would also recommend Sekiu Jetty, out near the northwestern end of the Olympic Peninsula ... as well as Salt Creek, closer along the Straits of Juan de Fuca toward Port Angeles. Both of those sites offer some fantastic diving, in relatively shallow dive sites. In both cases, there is spectacular scenery nearby ... with Sekiu being near Neah Bay and Salt Creek being not far from Hurricane Ridge and Crescent Lake. Hurricane Ridge would be a terrific stop for the non-diver who wants some great mountain views, while Crescent Lake offers lowland hiking trails, beautiful lakeside scenery, and a nice short hike to a waterfall. Both Sekiu and Salt Creek are within relatively easy driving distance to the Hoh Rain Forest ... for some of the northwest's most spectacular rain forest scenery ...
... Bob (Grateful Diver)