We'll be on the Carnival Conquest and in port at the Grand Caymans from 7-4 p.m. I'm leaning towards taking a Captain Marvins Stingray tour. He offers a 2.5 hour tour, a half day or a full day that ends at 3 p.m. What have others done? Wondering if the 2.5 is long enough? Or would you recommend more time? Thanks!