Copalis State Airport (S16)

www.wsdot.wa.gov/aviation/AllStateAirports/CopalisBeach...
en.wikipedia.org/wiki/Copalis_State_Airport

Located at the mouth of the Copalis River, this is the only known beach airport in the United States. The runway is the 4500 foot stretch of ocean beach from the Copalis River on the south to the rocks a mile north. The clam digging is excellent, and views are spectacular