Seagoing vessels frequently blend heavy fuel oil (HFO) with toxic waste and subsequently dump the oil in the sea. This contributes considerably to marine and air pollution. This chapter discusses the scope and nature of both activities. The high costs of legal waste management and the relative ease and impunity with which waste materials can be mixed with HFO or dumped represent a significant criminal opportunity structure. Law enforcement against hazardous waste processing at sea has tremendous limitations, which are related to detection problems and the strategic behaviour of the corporate owners of the vessels. Moreover, sanctions are often limited to financial penalties, which lack impact because the firms involved in the oil and shipping industry are among the world’s largest and financially powerful firms. Although naming and shaming is often presented as an alternative when enforcement is lacking impact, we argue that in the oil and shipping industry it might lack effectiveness because of limited media coverage of oil-related environmental incidents, the lack of “end consumer” contact, and the fact that the companies involved may be able to effectively neutralise negative publicity.