Waimanu Valley is a state campground for backpacking. It starts out at Waipio Valley lookout and continues 9 miles up to the next valley over. It's a moderately strenuous hike with a pack on your back! Be prepared with water filter, rain gear, mosquito repellant and everything else you need for backpacking. Check the weather in advance because there are two stream crossings that can get rather dangerous if it rises. Otherwise this is the most fantastic paradisiacal campsite on a beach you'll find in Hawaii! Less people than the popular Kalalau on Kauai. Research this one a ton and get permits far in advance!