The ideas developed here constitute some intermediary results of the Baguala project (uses of open environmental data in Latin America and France), which aims at understanding how Internet changes the ways the Society represents and manages its environment, through the supply of information and data online. In this short presentation, we will focus on the analysis of an inventory of websites that provide information or data about the environment in Argentina, Bolivia and Brazil. The main issue to be discussed here is whether we can characterize the structure of the "environmental web" at a national level, and with which methods. Who takes the initiative to share online data: institutions, individuals, etc.? What are the main problems and questions addressed by the authors of the sites which compose this "environmental web"? Can we detect groups among this group of websites, specialized subject? This perspective will allow us to understand the main patterns of the use of the web for environmental purpose, that means the strategies adopted by some social actors to play a role in the environmental debate or management through the creation of a website. This analysis will be developed here in an aggregated manner, comparing the structures of three environmental webs, the Argentinean, the Bolivian and the Brazilian one. Studying these three very different countries allows examining how social, geographical and technological factors affect the mains uses of Internet for environmental purpose.