Marni Rose McFall is a Newsweek reporter based in London, U.K. Her focus is on U.S. politics, social affairs and popular culture. She has covered fashion, culture, art and music extensively.

How much water you should drink each day depends on several factors, but generally healthy people need 4 to 6 cups of plain water each day, depending on what other beverages and foods they eat.

But for those who regularly order several alcoholic drinks a day when cruising, there's a way to save: a flat-fee drink package. Nearly all the major mass-market cruise lines offer flat-fee drink ...