Costa Cruises’ 3,724-guest Costa Diadema is a mega ship with all the bells and whistles you can expect from Carnival Corporation’s European-based cruise line. Sharing some of the same attributes as the ships in Carnival Cruise Line’s Magic class, Diadema has a wraparound exterior terrace encompassing a deck of public rooms, bars, and eateries that has the vibe of a seaside Italian promenade. The over-the-top decor by former Carnival architect Joseph Farcus makes Vegas look tame, adding to the frenetic pace of life on board. There are numerous entertainment venues, including a double-deck disco, a laser maze, a 4-D cinema, and even a race car simulator.