The best activity in Polynesia is going to a motu !
Motus are very small islands located in the lagoon and protected from the ocean by the barrier reef. Even though they are mostly privatly owned, it is possible to find some that allow you to stay for the day (for free or with a fee).
Last December (and two years prior to that) we stayed in Raiatea which counts a lot of motus. Have a look for yourself on this magnificent landscape…don’t you wish you were in the transparent water right now?