Costa Cruises’ latest, largest-ever vessel, the 3,724-guest Costa Diadema comes with all the bells and whistles you can expect from Carnival’s biggest European-based cruise line. Sharing some of the same attributes as the ships in Carnival’s Magic class, the 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, 4-D cinema, and even a race car simulator.