Alternative tourism (AT) contributes to conservation, valuing the environment and recipient cultures with minimal impact, especially in protected areas. In this context, this article identified, considering the residents’ perception, the possible environmental impacts resulting from alternative tourism in communities of the Tapajós-Arapiuns Extractive Reserve (RESEX), Brazilian Amazonia. Thus, between February and April 2019 a semi-structured interview was conducted with 122 residents of three communities of RESEX (Anã, Maripá, and São Miguel). The interview script was divided into three groups of questions: (i) interviewee data, (ii) socioeconomic data, and (iii) perception of the concept and environmental impacts of alternative tourism. We used a snowball sampling method, which consists of a form of a non-probabilistic sample. The majority (91.8%) of the informants did not know how to explain the concept of alternative tourism; however, for 87.7% of them, this tourism does not generate negative impacts. Income is the most used expression (53%) by RESEX residents to demonstrate what alternative tourism positively impacts. About 74.6% of respondents reported that tourists do not influence local customs change, and 94.3% do not identify tourism-related violence. Finally, 89.3% say that tourists do not pollute the environments. The research carried out in this Conservation Unit deserves the attention of decision-makers, managers, technicians, and researchers. It provides subsidies for management programs to provide real bases for the analysis, interpretation, and planning of sustainable tourist spaces.