This is a great hike for people who want to see the natural rainforest of Oahu. It follows a creek, with three waterfalls. There is a water supply pipeline following the trail part of the way. The third and final waterfall is amazing! You must scramble up alongside the waterfall, as it is very long and gradual. You must also cross it twice. After the ascent of the final waterfall, things become yet even more technical, when you must ascend a razor like crater edge in order to reach the summit of Kauu Crater. Kauu Crater is an old volcanic crater, which now harbors a swamp, in which is the source of the creek/waterfalls. Once at the the summit, great views of Waikiki and the other side of the island are plentiful! Plus the view of the crater inside. The crater and surrounding ridges create an echo chamber at a certain point along the ridge, see if you can find it. Use extreme caution when ascending the crater rim, as like mentioned, it is razor like, and one fall would be all it takes to end your adventures. A small part of the trail has recently been washed away, creating an extreme hazard when attempting to cross over it.
Follow Waiomoa Rd. to its end, and park at the provided parking lot near a large grass field. There is a bus that comes close to the road, but I'm not sure of the number or street it stops at. At the very end of the now small and windy road, there will be a fence, simply go to the left of the fence, and walk around it. It is there to keep cars out, not people, as it is very common to see others on this hike. Then, continue past the water pumping facility, and stay to the left, and you will be set!
This hike is fairly easy, as it is flat about half of the way. It has some technicalities after the first of three waterfalls. Technicalities include but are not limited to: creek crossings, small rock ledges, slippery rocks, ledges, and possible mud. Whenever rope is provided, there is usually a good reason, so use it to your advantage rather than as needed, after all, better safe then sorry! When you get to the third waterfall, you may notice ropes leading up alongside it, yes, you are going to climb it! It is not very steep or rough, at the most it is a scramble with occasional small ledges. You will cross the waterfall a few times. Once at the top of the waterfall, you'll see a trail leading upward to your right, take it, it will lead to the summit which from here out turns into a seemingly whole different hike, as it is open and narrow, leading up a crater rim. This portion of the trail can be quite dangerous, as one fall will end it all. It is like mentioned quite narrow, it is also quite steep, and is vulnerable to washing away, as a small part is nearing the middle of the rim. Once at the summit you'll see what you all the work was for, as there is a panoramic view of Waikiki and the other side of island.
"Working rule number twenty-three: Go through the motions anyway; you might get lucky."