Maritime transport is critical to the global economy. In a competitive environment, the industry is constantly seeking economies of scale and efficiencies. This has led to the introduction of larger vessels and an increasing use of information technology to achieve greater automation, both in ports and at sea. The technologies employed are vulnerable to the same cyber-security threats as those in other sectors affecting commercial, production and government systems. This article reviews the threats in the maritime environment and examines the need for increased awareness and protection of what are in effect maritime industrial control systems.