As ocean industrialization accelerates, corporate transparency is increasingly seen as critical to improve governance, yet little is known about how firms disclose their impacts on marine ecosystems. This study addresses that gap through a content analysis of sustainability and annual reports from 75 of the largest companies across 8 sectors of the ocean economy. We examine which impacts are reported, how they are measured and whether firms set related targets. Most companies focus narrowly on energy use and greenhouse gas emissions, with limited attention to more ocean-specific impacts, for which fewer than 25% of firms have metrics and targets. Where measurements are reported, the use of 443 distinct indicators limits comparability and suggests a lack of consensus on what should be disclosed. Amid growing demands for corporate accountability, our findings provide a timely benchmark to support the integration of ocean-specific considerations into reporting frameworks and to guide materiality assessments that better reflect the environmental realities of the ocean economy.