Lately I’ve slowly been rediscovering the hikes of my long lost youth and one of the first few I did was this nice waterfall hike in the back of Manoa Valley, which starts here: 21.328186,-157.799695. The bad news is it’s no longer that off the beaten path (as explained below). The good news is it’s still a nice hike, especially when it’s raining and more water is flowing.
Park near where you turn off Manoa Road. There is a gate with a no trespassing sign and the customary path around it. After that stay on the main rocky “road” (the same one that leads to Waiakeakua Falls) until you see a Porta-John and trail branching off to your left. Take that trail. It’s really the shortest and easiest waterfall hike in Manoa and the final falls are higher than Manoa Falls, though there is generally not much water coming over the final large falls.
The most interesting point to me is where a spur leads down to the right by a large banyon tree. There you can see where the majority of the water flowing in the stream comes out from a natural spring in the rock wall, next to a large boulder.
The trail now appears to be maintained by a local tour company which is running tours there in the mornings according to their site (BikeHawaii.com), so the trail is very clear and not at all the way I remembered it. With that in mind, there is officially no public access, part of the trail is on private property and they are making a living running tours there so it would be a very good idea to go in the afternoon, when you very likely won’t see another soul.