Harmony of the Seas | Show up. Show off. The largest and newest ship in the Royal Caribbean fleet features a top-deck full of adventure. Climb into the Ultimate Abyss and slide 10 stories down from atop of the tallest slide at sea, catch soaring aerialists in a jaw-dropping show, or head inside for some of the best dining at sea. Cruise with Royal Caribbean onboard Harmony of the Seas for a non-stop adventure packed journey.