The Gardner Pinnacles are two barren rock outcrops surrounded by a reef and located in the Northwestern Hawaiian Islands. The Pūhāhonu volcano responsible for the pinnacles is 511 nautical miles northwest of Honolulu and 108 miles from French Frigate Shoals. The total area of the two small islets, remnants of an ancient shield volcano, the world's largest, is 5.…The Gardner Pinnacles are two barren rock outcrops surrounded by a reef and located in the Northwestern Hawaiian Islands. The Pūhāhonu volcano responsible for the pinnacles is 511 nautical miles northwest of Honolulu and 108 miles from French Frigate Shoals. The total area of the two small islets, remnants of an ancient shield volcano, the world's largest, is 5.939 acres. The highest peak is 170 feet. The surrounding reef has an area in excess of 1,904 square kilometres.