The vision of a global cyberspace has inspired a lot of research in the field of Virtual Environments. However, virtual environments today remain island solutions, due to a diversity of incompatible data and protocol designs. In this paper we introduce the concept of Semantic Virtual Environments (SVE), a scalable approach to this problem, based on the W3C Resource Description Framework. SVE provides a unified machine understandable view on virtual environments, which is suitable both for processing by software agents and presentation to human users.