Several fine black sand beach locations can be found along the south coast of the Big Island. These are created when volcanic lava spills into the sea causing instant cooling and shattering of the black lava to create a black sand beach. These are often washed away in just a few months but when one is created in a natural bay with the right currents, the beach can last for hundreds of years. Two such beach spots can be found at Punalu'u on the south coast and Kehena east of Volcano National Park. ... more about Volcano Hawaii
At the very southern tip is another unusual beach which is khaki green in colour. Green Sand Beach is carved into an extinct cinder cone and requires either 4WD access to within a mile of the beach or a 3 mile trek along the dirt road before descending a steep trail to the beach.