So I didn't realize that you and your dh were going to Kauai!!! Have you been there before? We went there for our honeymoon and loved it.
If you haven't been there before, I have some recommendations.
We did snorkeling at Kehe beach (I think that was the name of it) on the north side and saw turtles. It's the last beach at the end of the main road on the north side of the island. If you are into roughing it and like hiking, at the end of that road, is a trail that runs along the coastline. It's absolutely beautiful! At one point there is a trail to hike inland and it takes you to this amazing waterfall. It's pretty tough hike and you have to cross the river several times, but it's so worth it.