The three forests between Poland, Lithuania and Belarous are a large preserved forest complex. These are: the Augustowska wood connected with the Grodzieńska wood, and the Rudnicka wood, located to the north. The central area between these forests is covered by an extensive peatland called the Holy Marshes (Čepkaliai), (total area of 6,000 hectares). Covered locally by marsh pine forest, the peatland lies in the edge of sandy plain within the watershed of the Katra, Ula and Gruda rivers. The author discusses significance of the peatland reserve not only as a refuge for fauna and native flora, but he also emphasises its historic and cultural importance.