Second homes are widespread in the Finnish countryside and represent a significant part of domestic tourism. In this paper impacts of rural second home tourism on natural environment and landscape are discussed mainly from a non-anthropocentric point of view and from the perspective of ecological sustainability. Both negative and positive impacts of second home tourism on nature, climate and landscape are distinguished. Environmental impacts caused by housing and living, shoreline building and physical mobility related to second home tourism are highlighted. It is argued that mobility related to second home tourism and year-round use of second homes are likely to increase in the near future and consequently pose negative environmental impacts. The argument is based on current societal trends and on results of a questionnaire survey conducted amongst second-home owners living in the metropolitan region of Helsinki and possessing second homes in eastern Finnish Lake District. There is today a large political will to enhance second home tourism in Finland, which is seen crucial for revitalizing the declining countryside. Contradictions between rural development policy on one hand, and environmental protection on the other, are critically discussed and ecological sustainability of second home tourism explored.