Great fun, great value, friendly and helpful staff. (Ryan was a great guide.)
We did not plan far in advance. We called Dukes around 9:30AM, asking if they had any availability that day. They did, 12;15 pm. (+1 for flexibility.) They gave good directions, a list of what to bring, and clarified before getting off the phone that they had a 24 hour cancellation policy. Since we were calling less than 3 hours before, they double-checked that I was ok booking the tour. Very honest.
The directions were easy to follow, and we arrived on time.
We signed a waiver, put our stuff in the provided backpack drybag, and hopped in the van for a 2 mile drive to the marina. After a brief (and sensible) safety intro, we got in our kayaks and got started. (btw, almost all the kayaks are 2-person, but that was ok with us.)
The trip up the river was easy, with the wind at our backs. We stayed as a group (4 2-person kayaks) and that meant a bit of waiting at times, but hey, you're on vacation, right?
A slightly longer than expected hike to the waterfall was not difficult, but could have been more dicey if the trail was wet.
Along the way, Ryan was telling us about the trees, the plants, and the fish. Not a "nature tour," but fun to hear about what's native to Kauai and what isn't.
The waterfall was great, albeit crowded, and taking a swim under it was a neat experience.
The paddle back was a bit tougher, (into the wind) but nothing to complain about.
We had a great time. You should go Kayak with this company!