Twin Rocks is an unincorporated community in Tillamook County, Oregon, United States, on the Oregon Coast. Twin Rocks, founded as a summer resort community, was named for two offshore rocks, 100 feet high, in the Pacific Ocean. Twin Rocks post office was established in 1914, with William E. Dunsmoor as the first postmaster. The post office closed i…Twin Rocks is an unincorporated community in Tillamook County, Oregon, United States, on the Oregon Coast. Twin Rocks, founded as a summer resort community, was named for two offshore rocks, 100 feet high, in the Pacific Ocean. Twin Rocks post office was established in 1914, with William E. Dunsmoor as the first postmaster. The post office closed in 1954.