Cooperation and communication play an important role for environmental governance. This holds true for the Baltic Sea in Northern Europe, one of the most disturbed ecosystems in the world, where insufficient cooperation between different stakeholders is one reason for goal failure. This article addresses the linkages between (media) framing on the one hand, and cooperation on the other. The case in focus is a set of negotiations related to the Baltic Sea Action Plan, the most central governance strategy in the Baltic Sea region. Our results show that in order to influence political decision-making, key stakeholders compete over the power to define and interpret problems, causes and solutions to an extent impeding cooperation. We focus the analysis on eutrophication, which we show to be a complex and controversial topic, framed in incompatible ways by different stakeholders.