Saltmarshes are extremely valuable but often overlooked blue forest ecosystems. They contribute to livelihoods locally and globally, through the associated ecosystem services they provide; including fish production, carbon storage and coastal protection. Despite their importance, knowledge of the current spatial distribution of saltmarshes has remained incomplete.In order to address this gap in knowledge, we have developed the most complete dataset on saltmarsh occurrence and extent at the global scale. Produced with support from the UN Environment/GEF Blue Forests Project, the dataset collates 350,985 individual occurrences of saltmarshes and presents the first global estimate of their known extent. The dataset captures locational and contextual data for saltmarshes in 99 countries worldwide, totaling 5,495,089 hectares of mapped saltmarshes across 43 countries and territories. This estimate is at the relatively low end of previous estimates (2.2-40 Mha), however, we took a conservative approach in the mapping exercise.Such data can support resource management, strengthen decision-making and facilitate tracking of progress towards global conservation targets set by multilateral environmental agreements, such as the Aichi Biodiversity Targets of the United Nations' (UN's) Strategic Plan for Biodiversity 2011-2020, the Sustainable Development Goals of the UN's 2030 Agenda for Sustainable Development, and the Ramsar Convention.