There is, of course, the Rock Creek Campground up the little stream and tucked in among the large spruce and Douglas fir trees in the Siuslaw National Forest. The trees are draped with moss and when the marine layer comes in, it could be the setting for a John Carpenter movie!
The creek lends itself and the outlet to the Pacific to fishing for Coho salmon and cutthroat trout. The beach area around Rock Creek is part of the Roosevelt Beach and at one time there was a small settlement.
The gravel beds at Roosevelt also provide agate finds like those at Lost Creek, Yachats, and beaches all the way to Haceta Head.
So the result of my research is: if the tide is high or coming in, the cars belong to fishermen and if it is a low tide (or especially a minus tide) the cars belong to rock hounds!
The cache is a quick stop, but you might catch one of the beautiful sunsets or views of the backside of Haceta Head. Enjoy the stop!