They provide information for beachgoers about the beach and its marine life. There is always a lifeguard on duty. As for the beaches with sands of different colors, Green Sand beach is located at South Point . It's difficult to get to, so skip it. Punaluu Black Sand Beach is located in Punaluu.
Swimming is cold due to many freshwater pools and it's a favorite spot for sea turtles.
There's also gray sand at Kona's Kahaluu Beach Park where snorkeling is at a premium.