Noroviruses are often most readily connected with cruise ships but this is incorrect. There are many more cases ashore than at sea. The reporting mechanism connected to the Vessel Sanitation Program and the work of health officials who track illnesses on cruise ships mean that shipboard problem are identified and dealt with more effectively than they are ashore. Often the problem emerges because the illness is carried onboard and then subsequently spread by passengers. The layout of a cruise ship with accommodation configured in close proximity is thought to contribute to the amount of interaction and person-to-person contract.