The Beach is a great summer bouldering destination - it faces north, is in Tumwater canyon next to the river, and is in the trees (except for the boulders on the beach itself, of course). Don't let the fact that it's on the other side of the highway dissuade you. Great selection of problems from v0 to v10, including the Fin (v2), Aggresive Reject (v9) and the Goicochea Problem (v10), most of which have great landings.
Getting There
Park at the outhouse pullout about 1 mile east of Castle Rock. Identifiable by the big rusty suspension bridge. Cross the bridge and follow the obvious trail for about 1/2 mile. When you hit the big boulder on your left that is almost touching the trail, you're there. You'll know this is the right boulder if you go around the backside - there is a big tree growing next to and touching the boulder.