Location: Hauula, Highway 83, just north of Sacred Falls State Park
Features: stream, gulch
This is a fantastic trail! It's a two-hour roundtrip through lush vegetation and gorgeous Maakua Gulch, with walls coming so close together, that you can almost touch them with both arms at a time.
The trailhead is at a bend in Hauula Homestead Road, about a quarter of a mile up from Kamehameha Highway. It's kind of hard to find.
There are actually three trails there, starting at the same point, a checkbox, where you can sign in, if you intend to go for a longer trip, or if you think, it might be safer to let somebody know where you went.
The trail to Maakua Gulch is not really easy, and I would avoid it during heavy rain, or if it looks like rain. The gulch is known for flash flooding so it might be better to check the weatherconditions before you start.
We were lucky, because when we hiked the trail, the streams were almost dry until we got the little pool at the end of the signed trail. But when we saw the riverbeds we had to cross (fortunately without water), we could imagine how it must be during rain. There must be over a dozen stream crossings on the way, we stoped counting after half an hour. The trail is marked with red tags which are sometimes hard to spot.
Nevertheless, the last 10 minutes you have to go along a stream, which even runs during the driest conditions, so bring good shoes.
The official end of the trail is at a small pool, with a tiny waterfall. I bet the gulch still continues after that point, but without the proper equipment, it's probably suicide...