Lots of visitors who come to Kauai want to hike to a waterfall and I have just the one for you. In fact, on this hike you get two falls for the price of one hike and it is free. Ho’opi’i Falls is on the Kapa’a Stream.
The trail can be very muddy with lots of mosquitoes if there has been a lot of rainfall. The two times that I went to the falls were in the middle of summer and it was dry and pleasant. This video, taken in July 2017, by Clifton Passow, will give you an idea of what the trail is like: