Carnival Horizon passengers tend to be a fun-loving group hailing from all over the world -- but especially the United States. The ship's multiple cabin options and myriad activities appeal to families, and you'll see all kinds of kids onboard especially during the summer and over the holidays. Couples across all age ranges are common, as are large groups sailing together.

During the day, relaxed and casual is the name of the game. Virtually anything goes, though swimsuit attire is restricted to the outdoor spaces and men are required to wear shirts with sleeves to the main dining room. In the evening, Carnival Horizon adheres to what they call a Cruise Casual dress code. For women, that means beachy dresses, casual skirts, pants or capris, jeans or dressy shorts with blouses. Men are requested to wear items such as sport slacks, khakis, jeans, long dress shorts and collared shirts.

On formal or elegant night, main dining room attire is fancier, with men wearing suits or dress pants with dress shirts and sport coats. Tuxedos are rare but not unwelcome. Women wear cocktail dresses, pantsuits, evening gowns or elegant skirts with blouses. Not all passengers participate in formal night; passengers who wish to skip it can dine at the Lido Restaurant wearing casual clothing instead. Still, you're likely to see a few passengers wearing more casual clothing in the main dining room on formal nights. Carnival Horizon sailings of two to five nights have one cruise elegant evening; sailings of six nights or longer have two.

Carnival Cruise Line automatically adds a $13.99 per person, per day gratuity to onboard accounts. (Suite passengers pay $15.99 per person per day.) The tips are split among the crew who serve you each day: room stewards, and waiters and assistant waiters, for example. Passengers can prepay gratuities before they board Carnival Horizon or adjust them at any point during their cruise by visiting the passenger service desk. The gratuity policy applies to passengers 2 years and older.

All bar bills and spa treatment purchases come with an automatic 15 percent gratuity, which is not optional. You can tip room service staff in cash -- a buck or two is appropriate though not required.