Zac Brown Band celebrated their 15th straight sold-out concert at Fenway Park in Boston Sunday night with a huge surprise. More than 37,000 fans at the concert were given a free cruise for two aboard Margaritaville at Sea. “I’m buying every single person here a cruise for two people on the boat. The band has been giving away four cruises at each show on this current tour in a promotion with Margaritaville at Sea. Zac Brown Band played their first show at Fenway Park back in 2014.