Socioeconomic status (SES) as well as adolescents' perceptions of the neighborhood's built and social environments have been shown to influence adolescents' physical activity. Twenty-four adolescents from two low SES neighborhoods in Sweden participated as citizen scientists, using the Stanford Discovery Tool app on their phones to take photographs and record audio narratives of aspects of their neighborhood that they perceived facilitate or hinder their physical activity. The most frequently reported facilitators were ‘parks, playgrounds and outdoor gym’ as well as ‘amenities’ and ‘sport facilities’, whereas lack of or shortcomings regarding ‘bikeability and walkability’, ‘personal safety’ and ‘lighting’ were the most frequently reported barriers. The results will be used to inform local politicians and policy makers about new ways to improve physical activity among residents in Sweden's low SES neighborhoods. Also, this study shows that a Swedish version of the Discovery Tool app is acceptable and can generate useful information in the context of adolescents from disadvantaged neighborhoods.