Caption:Mahana Bay is located just north of the southernmost tip of the United States, Ka Lae (South Point) on the Big Island of Hawai'i. It is a beach full of green sand. In order to get to the beach one must walk three miles on a four-wheel drive road. It is north of Kaulana Bay. The beach was made by volcanic phenomena. Instead of the sand turning black it turned green. Big chunks are called olivine. It is also known as peridot, the birthstone for August.