Wet tundra environments of the Siberian Arctic are natural sources of the climate relevant trace gas methane. In order to improve our understanding of the present and future carbon exchange in dynamic permafrost environments the methane content as well as the activity, diversity and physiology of the methanogenic community have to be studied. For these investigations permafrost soils as well as terrestrial and submarine permafrost cores of Holocene and late Pleistocene ages from the Laptev Sea coast have been used. The results indicated the existence of a permafrost microbiota, which has well adapted to the extreme environmental conditions. Furthermore, first evidence of modern methanogenesis in the perennially frozen sediments was given by microbial activity and PLEL analysis. The characterization of pure cultures of methanogenic archaea obtained from permafrost environments showed an unexpected resistance against extreme living conditions such as low temperature, high salinity, desiccation and starvation.