We felt the same way until I called the resort and they mailed me an itinerary of what is going on during the week. There are all sorts of activities, like the marsh tour which we enjoyed, (I have 2 boys, 5 and 9), the bird watching was not good for the boys, but we still enjoyed it, there is a puppet show, magic show, camp fires w/smores, etc... but most of all, we rented bikes and went all over the place on the paved bike trails that are on the island. That was the best for my family. As for your 18 year old, I'm sure there will be other things for her to do. Email the HHI chamber of commerce, you can find it on any web search and ask them to mail you stuff. We are going there in 2 weeks and can't wait!!! ENJOY!!