Wireless sensor networks for environmental monitoring promise to be a rich source of ecological, biological, and meteorological data. However, current systems largely return data to a central location for offline analysis, and do not support access by mobile users in the instrumented environment. In many environmental monitoring applications, it is critical to support users in the field so that they can correlate manual observations with the sensor network data, engage in system topology adjustments and calibration tasks, and perform system management. However, it is critical that such mobile users do not interfere with the regular data collection functions of deployed systems. One of the critical systems functions needed to support mobile users of wireless sensor networks is routing. In this paper we iden- tify key mobility usage scenarios and present Hyper, a routing layer that enables efficient and reliable data collection for both static and mobile users.