Discusses the challenges of achieving lower emissions from marine engines without penalizing fuel efficiency or raising costs in other areas. Controls to date have mainly focused on oxides of nitrogen and sulphide, but smoke and particulates and carbon dioxide formulation are coming under increasing scrutiny. The article looks at measures being taken to control emissions and associated environmentally-friendly vessel designs. It details the use of LNG as a low emissions bunker fuel in a new generation of Norwegian ferries, fuel cell developments, and fuel cell guidance from Germanischer Lloyd.