The last of Royal Caribbean’s five Voyager-class ships, Mariner of the Seas was launched in 2003 and was the first (in 2012) to get Royal Advantage upgrades featuring signature amenities of Oasis-class ships. It was also among the first to be “Amplified” (in 2018), which added even more activities and dining options. That means this 3,344-guest ship’s 15 decks are packed with activities (rock-climbing, ice skating, a surf simulator, laser tag, a space-themed escape room, mini-golf, three pools, six hot tubs, looping waterslides, and a poolside movie screen), along with nine dining venues (including Jamie’s Italian by Jamie Oliver, Izumi Hibachi & Sushi, and Chops Grille), and 13 bars and lounges. Yet despite its size, Mariner of the Seas rarely feels crowded.