One of the few remaining places in Hawaii to see a black sand beach, Waipio Valley has a nice stretch of almost unused beach. Perhaps the reason is that it takes a 4WD truck to get down there. The sloap is so steep that your 2WD will probably slide down the mountain dangerously.
If you are adventrous and have 4WD, driving down the steep hill to the vally floor will reward you with black sand beach, streams and taro patches. We drove down with Chevy Trailblazer 4WD on low gear, crossed a few streams, and made it to the beach. Access to the beach is easier to make on the way upward to the left, rather than to make a sharp right hand turn as you descend. Most of the rental company will prohibit you to drive down this road, check with your rental Co. Rule of the road is that the car coming upslope has the right of the way, and you should make a room by pulling to the side. The road is barely big enough for one full sized SUV, therefore look out whether anybody is coming up. You could hike down to the vally, but walking up the hill would be very exhausting..Either way, you will be rewarded with the most gorgeous black sand beach you could imagine in Hawaii.
Perhaps one of the best experiences you'll have aside from standing at the lookout would be horseback riding. Off in the distance you can see an old mule trail.