Zac Brown Band gives free cruises to 37,000 Fenway Park concert fans in "incredible surprise"

Zac Brown Band celebrated their 15th straight sold-out concert at Fenway Park in Boston Sunday night with a huge surprise. Everyone in the audience got a free vacation on a cruise ship.

More than 37,000 fans at the concert were given a free cruise for two aboard Margaritaville at Sea.

According to the band, the total cost of the gift is more than $40 million - all paid for by Brown.

Brown broke the news to the crowd just before their performance of "Same Boat."

"I'm buying every single person here a cruise for two people on the boat. Every single person here gets a cruise for themselves and a loved one to go on the boat," he said in a video provided by the band. "This is the biggest giveaway in history, ladies and gentlemen, here tonight at Fenway Park!"

"We were honored to work alongside Zac to help bring this incredible surprise to life for his fans," Christopher Ivy, chief executive officer of Margaritaville at Sea, said in a statement. "This was an extraordinary way to thank the fans who have supported him throughout his career, and we're proud to have helped make that incredible vision a once-in-a-lifetime reality."

The cruise gifts can be redeemed on "select Margaritaville at Sea sailings over the next year," according to the company.

Fans who were at the show were shocked when they got the free cruise.

"At the beginning of the show, Zac Brown announced that there was going to be this amazing surprise that was taking place during the concert," said Serina Ryder, who was at the show with her three sons. She thought the band would be bringing out a surprise guest. "But I never thought when he announced that he would be giving away a free cruise to every single person in the audience that we would be getting that kind of gift."

Nathan Whitcomb was at the concert with his girlfriend and his parents. "I was like, 'is he serious?' I didn't believe it, it didn't seem real," Whitcomb said. "It was unbelievable. Something so generous and it was just amazing. I'm still speechless. I woke up this morning, and I still couldn't believe it."

"This was definitely an amazing surprise that we weren't, nobody was anticipating," Ryder said. 

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.