Cruising has become a major part of the tourist industry. In 2010, the total passengers carried worldwide was estimated at 18.4 million, on about 230 cruise ships. Large ships can hold up to 6,000 passengers and > 2,000 crew members. A large cruise ship is rather like an island, with two different communities: the well-trained crew, hopefully prepared for every eventuality and trying to make their guest's stay as pleasant as possible; and the guests, there to have fun. The guest population varies, with up to 40% under 21 years old during school breaks, and the average age is in the fifties or sixties on longer cruises to scenic places such as Alaska. Most of the time ships cannot be reached by helicopter and the medical teams need to cope with a wide range of emergencies from cardiopulmonary, trauma, and psychiatric issues. There are strict public health measures enforced and a range of legislation reducing the risks of cruising to a minimum. This paper reviews the training of the crew for medical emergencies, the incidence of disease, the incidence of medical disembarkation and major incidents on board, and the role of medical teams.