||VGI represent today a significant form of user-generated content compiling information about locations (e.g. places of interest), a phenomena or information (e.g. GPS tracking of bike and hiking routes), and can be stored into interactive track management services (e.g. Web 2.0 platforms) (Rinner et al., 2008). The present explores the use of GPS-based visitor tracking data organized in a Web 2.0 platform as an alternative resource to assess the spatial distribution of informal trails networks and their level of impacts in protected areas. It has is application in Arrábida Natural Park (PNA), an important protected area in Portugal, located 37 km south of Lisbon, where informal trails are a constant management concern due to a lack of a structured and formal trail system, leading to some impacts and extensive areas of disturbance.