The Hawaiian island known for its black sand beaches is Big Island.

The Big Island of Hawaii is famous for its unique black sand beaches, created by the island’s volcanic activity. As lava from eruptions cools and breaks down into small particles, it forms black sand, giving these beaches their striking appearance. Popular black sand beaches like Punalu'u Beach are found on the Big Island, attracting visitors for their beauty and geological significance. These beaches are also important nesting sites for sea turtles. The Big Island’s volcanic landscapes and dramatic coastlines make it a must-visit destination for nature lovers and adventure seekers.