My wife and I went on this tour last week and loved it. We saw hundreds of spinner dolphins, several turtles (my wife swam right next to one for a good minute) and even a few humpback whales which are now making their way back to Hawaii from the north.
The crew, who were all Marine biologists, were all extremely friendly, knowledgeable and respectful of the wildlife that they took us to.
The only negative: Lunch served afterwards was not very good, and they sell pictures at the end (DVD you get mailed) for $57 which is high considering you don't get to view the pictures before purchase. Definitely bring your own waterproof camera and enjoy an amazing tour.
If you own or manage Dolphin Excursions Snorkel Adventure, register now for free tools to enhance your listing, attract new reviews, and respond to reviewers.