Abstract
Crimes committed on board a ship, particularly when at sea, pose a more dynamic legal scenario than the same crime committed on land. A ship is subject to the laws of its flag state, but a criminal act committed on board will almost inevitably lead to an overlap in jurisdictional claims. This article considers the various factors that determine when and whether states other than the flag state may claim jurisdiction to prosecute criminal acts committed at sea, and compares the claimed extra-territorial operation in the domestic laws of four states. It also considers the recent introduction of cruise ship regulation in the United States, the moves to introduce guidelines in Europe, and supports the momentum building towards regulation of the cruise ship industry in Australia.