Royal Caribbean Classic's Oasis of the Seas is the World's Largest Cruise Ship. Oasis of the Seas is the largest and most revolutionary cruise ship in the world. An architectural marvel at sea, she spans 16 decks, encompasses 225,282 gross registered tons, carries 5,400 guests at double occupancy, and features 2,700 staterooms. Oasis of the Seas is the first ship to tout the cruise line's new neighborhood concept of seven distinct themed areas, which includes Central Park, Boardwalk, the Royal Promenade, the Pool and Sports Zone, Vitality at Sea Spa and Fitness Center, Entertainment Place and Youth Zone. The ship will sail from her home port of Port Everglades in Fort Lauderdale, Fla.