<p>The study focused on reconstruction of the extreme hydrological changes within the bog surrounding the lake Płotycze near Sobibór over the past 200 years. The site has been located within the reserve „Three Lakes”, in the Sobibór Landscape Park. The main aim was to determine the intensity of these changes and to determine the extent to which allogeneic and indigenous factors resulted in the functioning of peat bog. Analysis consisted of 0.60 m peat core extracted from the northwestern part of the bog, including the youngest periods in the history of the bog. This section, as follows directly from historical data, is also a carrier of data on intensive human impact on the area. As a research method testate amoebae analysis was used. These organisms belong to the dominant group of peat microorganisms. The results obtained enabled to determine two main paleohydrology phases in the last 200 years of the peat bog history. These phases have been correlated with historical data and with the results of previous studies carried out in the peat bog, i.e. reconstruction of water level changes based on data mapping using GIS tools and the study of plant communities.</p>