Cupsogue is a strange name for a park. It sounds like a local Native American term. Wikipedia confirmed my suspicion. “…dated from the 1690’s, local Indians called it Cupsogue meaning “closed inlet,” A 1931 nor’easter opened it again and it was widened during the hurricane of 1938. I suspect that the location and narrowness of the barrier beach has caused it to open and close several times over centuries. Perhaps local Indigenous residents witnessed one of its closings.
The park is located at the dead end of Dune Road. It is fronted on three sides by water, the Atlantic, Moriches Bay, and Moriches Inlet. The inlet has been bolstered by two long rock jetty’s to curtail erosion. On either side, 15 foot high iron towers mark the opening.