Kehena Beach, Hawaii is an amazing place with sand that is black as night. It is made from the naturally flowing lava found in this area. .Located in the Big Island’s Puna district, Kehena Beach is one of the few unofficial “clothing optional” beaches in Hawaii. It is a long, but narrow black-sand beach, which local residents also call Dolphin Beach because of the frequent appearances of spinner dolphins in this area..Kehena beach was formed in 1955 when lava flowed down the sea cliffs and into the ocean here. At the eastern end of the beach, one can still see the tip of the lava flow (which is now a rocky point of land) that created the sand.