Technology to provide realistic virtual natural environments (atmosphere, ocean, and space) for distributed simulations is a relatively recent development that will have a wide-ranging impact on the next generation of constructive, manned trainer, and analysis simulations. Significant recent research has laid the groundwork for expanding growth in this area and the introduction of these new levels of environmental realism in operational simulations. This paper describes a vision of how these emerging technologies will form a unified framework for creating, managing, modifying, and distributing environmental data and effects. Technologies to enable this vision will be discussed, including: desktop numerical weather prediction models for user-controlled weather scenario pre-exercise generation; interactive run-time modification of the environmental state to support exercise control; production of exercise meteorological and oceanographic chart products that reflect imperfect forecasting or data acquisition capabilities; and architectural options for enabling environmental effects computations to meet different simulation requirements. The state of the art in these areas, as well ongoing research that will lead to twenty-first-century system implementations, is presented.