Hidden (not so hidden) Gem
Polihale is the beach you go to if you are looking for a beach with very few others on it. It's the last beach when driving out to the west side. If you hit the end of the road, you've gone too far. The road out is pretty terrible so if you don't have a car that can handle some bumps, I wouldn't risk it. There are countless times when tourists take their rentals out there and get stuck either in the sand, mud or potholes.
If you manage to make it out there, you will have a good chunk of the beach to yourself. There a pavilions and picnic tables scattered throughout the stretch of beach. My personal favorite is to just throw a towel on the sand, watch for shooting stars, and fall asleep. There is no light pollution so this is also the place to go to capture those beautiful night sky shots.