The ISMN Data viewer is a tool that can be used for viewing and downloading in-situ data. To view the data, press "Data Access" button on the left side of the page. User registration is not necessary for viewing the data. The data viewer embeds Open Street Map, an open-source and freely available service, which offers the user a map-based selection tool to view and download the available data. By clicking on the markers, the user obtains a summary of important metadata about the networks or stations, respectively, depending on the zoom level.