The development of national nature observation databases, including data on field observations and museum collections in Estonia, Finland and Sweden, has reached to the crossroads: the museums have found out that they host and plan to develop their nature observation and collection databases in a closely similar manner. The major museums all aim at an open access to the nature observation data and have an ambition of national coverage of most of the known species. However, transnational joining of these databases has up until now not been done. The partners of project BALTICDIVERSITY are making their first attempt in developing the data exchange and joint platforms between the national databases. This helps to address the transboundary problems, like impact of climate change on biodiversity. The project has come up with a solution on how to connect data of the major natural history museums in the region into an interoperable whole in order for this data to be better used for decision making in nature conservation, research and education as well as by the general public across borders. For instance, comprehensive species distribution datasets from wide geographic areas over the Central Baltic Sea region are built and made publicly available.