Puerto Vallarta (PVDN) - Puerto Vallarta is gearing up for a busy April with the arrival of 20 cruise ships, adding to the more than 200 expected for the year. The month kicked off with the Zaandam and National Geographic Sea Lion docking at Pier 1 and Pier 3, respectively, on April 1. The Sapphire Princess arrived at Pier 1 on April 2, followed by…