Hi'ilawe Falls is at the back of Waipio Valley, accessible by either an easy or difficult hike depending on the recent weather. Some days it's unreachable altogether if the stream is too high and dangerous. The day we went was a beautiful sunny day, but the past two days had been rainy so we didn't know what to expect. The road down into the valley is passable by any two wheel drive rental car. Some hiking and trip reviews tell you to only drive down the road if you have a four wheel drive. On a rainy day a four wheel drive might make it back up the road easier; but really, it's no steeper than any hill in San Francisco or the mountains of Israel. Having driven all three, those are the best thing I can compare it to. No I didn't bother to take a picture of the road. It's a road. It's steep. Hey look there's the first good view of the valley as you head down the road.
The other reason I wanted to visit this spot is for the black sand beach which is where we ended the day. On arriving at the bottom of the valley it's not clear where to go next. There aren't any signs for the trail and if you're not careful you'll be parking on someone's private property. This is probably why most people hike down the road instead of driving. Immediately after you cross the main stream (which may or may not be obvious) head south into the valley. The trail follows the right hand side of the stream for a ways and then criss-crosses it several times as you wind your way towards the back of the valley and the falls.
Since it had been raining for two days, there was quite a bit of water coming down the stream, and in one spot, absolutely no way to get through other than to wade up the stream. It took us about an hour and half to navigate the trail and reach the falls. That's my brother-in-law on the slope and my wife in the water. They're both just a bit taller than I am, and I almost turned back, thinking my cameras and lenses didn't really need a bath in that cold water.
We all managed to make it through the deep water crossing with dry shoes though. If you can make it to the falls, the sight will probably be worth the hike. If the weather has been dry there won't be much if any water. There was so much water coming over the falls that it was too wet to take photos from the base of the falls. I had to go back downstream a bit for some shots.
After hiking back out, we spent a couple of hours on the black sand beach. About half of the beach is wave washed stones and the other half is just soft black sand. Plan a whole day in the valley and you can make it to the falls with plenty of time to enjoy this beach that you might just have all to yourself.