Since a lot of the sand on this side of the island is lava based (basalt) you will find many areas with black sand. It is a beautiful difference from the white sand that you would normally see at most beaches. And dont forget! Keep your eyes peeled. There are certain areas where the beaches are not crowded. Most of them do involve hiking as they are usually infront of beachfront homes. But A lot of the time, due to this lack of crowding, Hawaiian Sea Turtles (Honu) hang out here by the shore and occasionally come up on the beach to get some sun.
Breathtaking to watch the waves crash against the rocks as you emerge from your car, finally your eyes turn to view the sandy beach. Yes, it is like some alien landscape. But so beautiful. And windy. Look out for Green Sea Turtle nesting grounds. They are a protected, endangered species, but are fun to watch - if they decide to stop sunning themselves and move an inch!
visit the black sand beach (Hawks billed turtle refuge), the volcano, Pahoa(hippie town), snorkel, body surf, eat at the Ocean Breeze (real Hawaiian food cheap) and Cafe Sibu. And of course don't forget the Kona Inn for the best dining and drinking seat on the island. Watch the sunset and see if you can see the blue flash. Its no joke.
South of the Hawaii Volcanoes NP, you'll come across an astounding sight. Black-sand beach's appearance is a result of ocean waves wearing down and crushing volcanic rocks and debris.