In this paper, the history of Durne Bagno, i.e. the largest peat bog in the Lublin Polesie, is shown. Peat bogs are a unique element of the Polesie landscape. They occur mostly in the subregion of the Łęczna-Włodawa Lake District occupying 1.07% of its area. They fill basin-shaped depressions without outflow, often in the immediate vicinity of dystrophic lakes. Based on interdisciplinary research, the changes of vegetation cover and the Durne Bagno lake-mire ecosystem in the Late Glacial and Holocene are presented. The environmental conditions are reconstructed from pollen analysis, detailed identification of algae of