We did this in 1999 and it was great - 1/2 day, they took us to two great spots and then added a dive with sharks, very cool. They used chum to attract them, then lowered the "bait" in a box down about 30 ft so you could snorkel above them-the sharks couldn't have cared less about the people in the water. The snorkeling was much better than at Coki Beach from the cruise.