Marietas Islands: Cavern Swim and Snorkel Cruise from Puerto Vallarta. The Bay of Banderas and the Mexican Pacific offer a vast array of wildlife and are available for you to explore during this exciting day tour. You'll have the opportunity to discover the wonders of nature while looking out for dolphins, whales, giant manta rays, sea turtles and tropical fish, all in their natural environment! Complete with bird watching, swimming, snorkeling, scuba diving and kayaking in the warm waters that surround the Marietas Islands, this eco-adventure provides for an exciting itinerary on your Puerto Vallarta vacation! Book with us and Save 11% Off Marietas Islands: Cavern Swim and Snorkel Cruise from Puerto Vallarta.