We chose Calypso for our scuba/snorkel trip while staying in Port Douglas from a list of a variety of tour operators. We picked them based on a recommendation from our hotel and coincidentally, our guide at the Franz Josef glacier in New Zealand, who used to work for them. We weren't disappointed. Unlike many of the dive trips, which feature huge boats with up to 300 hundred people, and often go to a permanent submersible at the reef, our boat had no more than 30 passengers and went to three different dive sites. We chose to do two dives and one snorkel and all three were amazing experiences. The guides were very well trained, knowledgeable and serious about each person having a fun and safe day at the reef. Our dives were some of the most memorable experiences of our 2.5 week honeymoon; this was the first time scuba diving for both my husband and me. We'd highly recommend Calypso to anyone looking to book a tour to the GBR.