There are a couple trails here worth exploring. The easier of the two is the Kulioou Valley Trail which can get a bit tricky when it's wet. The other worth checking out is the ridge trail which is a bit more technical. The ridge trail brings you up to the top of the ridge with great views. Both trails offer lots of shad and are loads of fun.
How to get there:
Just before you get to Hawaii Kai heading East turn onto Kulioou Valley road and head into the valley. Go as far up the valley as you can and turn right at the last street. Follow this street up even more to its end and the start of the trail.