Microbial processes of the methane cycle were studied in four lakes of the central part of the Yamal Peninsula in an area of continuous permafrost: two large, deep lakes and two small and shallow ones. It was found that only small, shallow lakes contributed significantly to the overall diffusive methane emissions from the water surface during the warm summer season. The water column of large, deep lakes on Yamal acted as a microbial filter preventing methane emissions into the atmosphere.