To earn the designation, a black beach must contain a specific type of underwater rock that turns into dark sand over millions of years. Rocks in the Marin Headlands are referred to as a ...

U.S. News Insider Tip: Snorkeling around Black Rock is some of the best on the island. On the other end of the beach, if you're staying at the Hyatt Regency Maui Resort & Spa, ask about the hidden ...