Travel by sea is one of the earliest forms of transportation. From ancient times to the present, people have traveled by ship for purposes of food obtainment, trade of goods, conquest, employment, and leisure. Before ships were built large enough to take long ocean voyages, the most relevant medical problems included drownings, injuries, and attacks by alligators, sharks, whales, or other sea creatures. It was only after ships sailed for more than a day or two that questions of food and water supply, sanitation, ventilation, care of the sick and injured on board, spread of plagues, and transmission of infectious diseases began to arise. An estimated 4.5 million passengers travel on cruises in North America annually [1].