We've just came back from our Carribean-cruise with Celebrity Millennium and I wanted to highly recommend the best trip we did in these few days.
In Curacao we did the world of water-tour with Curacao-Actief, what was recommended by some of the chat members here. And it was totally great!!!
There were just we two and our guide Sander who gave us a day with lots of fun and great moments. After passing the mini-dessert (with lots of birds, iguanas and so on) we came to a cave with many bats inside...just we three were in there. After we had some great views of the rough Northern Coast and a nice lunch, we went swimming to a beach of our dreams (with almost no people there). But the absolute highlight was the snorkeling at the end. We saw so many different kind of fish...and we swam with a turtle...just a few centimeters away from us. And the best of it...just again we three and no one else there.
The tour isn't cheap, but in comparison to all our other excursions, it was absolutely worth every cent!