This presentation focuses on the impact of nature-based activities on protected areas from an environmental sociology perspective. Without denying their ecological effects (Ng, Leung and al., 2018), this approach underlines that those impacts also raise social issues, as with all environmental considerations (Candau and Deldrève, 2015). We argue that managing these activities on the basis of their impact on the natural environment is an "environmental effort" for users, that is to say a socially differentiated and potentially unfair contribution of social actors to environmental protection policies (Deldrève and Candau, 2014). Considering nature-based activities only as a potential hazard for environmental protection may have the same social effects as categorizing overuse as a danger (Claeys and al., 2011). In addition, it could lead to the exclusion of human populations from the territory, and may create or accentuate environmental inequalities (Deldrève and Candau, 2014). Since the 1980s, this issue has become a topic of increasing interest for policy makers and researchers, under the influence of the "Environmental Justice" movement in the United States. More recently, both have been recognized as a crucial issue, even in outdoor recreation (Taylor, 2000). Ecological paradigms as well as the political and legislative international contexts in which these protected areas are developed have also evolved to better recognize human activities. But what are the concrete effects of these evolutions in terms of environmental effort? Who defines environmental effort for users in natural areas and how is it argued? What principles of justice govern the arguments put forward by different stakeholders? What are the different forms of effort and how different stakeholders judge them?