Most visitors to Orcas Island focus on Moran State Park, which is indeed beautiful, but a little further south along Olga Road you will find Obstruction Pass Park, an 80-acre recreation area.
This is a great spot if you want to get away from the crowds, and the view of Obstruction Island from the beach is beautiful.
The park has nine hike-in (1/2 mile) camping spots and a lovely pebble beach. The campsites are first-come, first served & no fee. Primitive facilities only (vault toilets, no water).
We made this a half-day trip from our campsite at Moran, and our kids had a great time splashing in the water and collecting bits of driftwood, crab shells and sea glass (which we left on the beach, in keeping with "leave no trace" principles!).