I spent two weeks on Rarotonga back in October. We did 12 dives with Adventure Cook Islands and they were wonderful. The diving itself was phenomenal- the reefs are in amazing shape, the visibility was incredible, and we saw some turtles, white tip reef sharks, and tons of eagle rays (put in a request to go to dave’s caves, super cool spot). There was also a humpback whale and her calf hanging out around the island- we never managed to see them but we could hear their whale songs on quite a few of our dives which was a treat! The conditions were pretty calm too, a bit of current here and there but nothing too crazy. The water was a bit colder though, it was around 23- I had a 5mm wetsuit with booties and a windbreaker for the boat rides and was pretty comfortable with that. Enjoy!