One of the nicest excursions we did was the lagoon discovery with snorkelling in Moorea. A very laid-back, fun morning. This is where we were snorkelling with the stingrays. Also, went on a small island where I was the only one there. I walked from the boat (my husband was snorkelling) in waist deep water to get there. It was great!! The trails of the ancients was very informative as well, but got old after about 2 hours of trekking!!
j.