Watervogels - Wintering waterbirds in Flanders, Belgium is a sampling event dataset published by the Research Institute for Nature and Forest (INBO). It contains information on more than 94,000 sampling events (bird counts) with over 720,000 observations (and zero counts when there is no associated occurrence) for the period 1991-2016, covering 167 species in over 1,100 wetland sites. The aim of these bird counts is to gather information on the size, distribution and long term trends of wintering waterbird populations in Flanders. These data are also used to assess the importance of individual sites for waterbirds, using quantitative criteria. Furthermore, the waterbird counts contribute to international monitoring programs, such as the International Waterbird Census (coordinated by Wetlands International) and fulfil some of the objectives of the European Bird Directive, the Ramsar Convention, and the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA). Here the dataset is published as a standardized Darwin Core Archive and includes for each event: a stable eventID, date and location of observation, and a short description of the sampling protocol, effort and conditions (in the event core), supplemented with specific information for each occurrence: a stable occurrenceID, the scientific name and higher classification of the observed species, the number of recorded individuals, and a reference to the observer of the record (in the occurrence extension). Issues with the dataset can be reported at https://github.com/inbo/data-publication/issues The following information is not included in this dataset and available upon request: roost site counts, counts from historical (inactive) locations. We have released this dataset to the public domain under a Creative Commons Zero waiver. We would appreciate it if you follow the INBO norms for data use (https://www.inbo.be/en/norms-data-use) when using the data. If you have any questions regarding this dataset, don't hesitate to contact us via the contact information provided in the metadata or via opendata@inbo.be.