Great experience.
Very friendly captain and crew.
We ran on engines to the end of Duamond Head, where we found some whales, then drifted back with the engines cut using the wind to push the catamaran along, following the whales.
We weren't lucky enough to see a whale fully jump out of the water, but we did see a boat a dozen whales, three or four tails out of the water, and a 40 footer swam right alongside the boat at one point.
Highly recommended.