What is there to do in the South Pacific?

So my family and I are planning a 3 wk trip to the South Pacific, we have been to Hawaii and Tahiti before but we all have different interests! some of my kids like adventure and thrills and some like peace and quite like my husband and I. I know about snorkeling but how about other things for kids? maybe more info on dolphin swims! What would be a good day out on the town or hike through the rainforest something like that!!

You can rent a small outboard motor boat like we did in Bora Bora ... visit small lagoons, swim etc...