For our last full day on Tahiti, I went on a 1 hour Jet Ski tour (did not bring camera) where we just cruised around and spotted some dolphins and looked for whales (did not find any).
Then I finally did something I had been hoping to do for the whole trip and that was to go snorkeling at night on the reef under our bungalow. And I am so glad I did! I started when it was still light, but continued until after sunset.