A handful of companies dominate the world’s shipping industry. These firms have gained political leverage over the global governance of container shipping in particular. Intriguingly, in recent years the Danish conglomerate Maersk—the world’s biggest container and shipping vessel company since the mid-1990s—has been using its influence to push for higher environmental standards for the industry as a whole. To some extent these initiatives are helping to promote environmental efficiencies, cleaner fuels, and greener technology. But they are also raising costs for small and midsized companies with extremely low profit margins, further enhancing the competitiveness of the biggest shipping conglomerates in an increasingly oligopolistic market. While voluntary self-governance by companies such as Maersk is incrementally improving the environmental management of global shipping, it is also further concentrating governance power within a few transnational corporations, potentially taking more ambitious regulation off the agenda.