We describe UbiWise, a simulator for ubiquitous computing. The simulator concentrates on computation and communications devices situated within their physical environments. It presents two views, each in a separate window on the desktop of the users' PC. One of the views provides a three dimensional world, built on the Quake III Arena graphics engine and serves to simulate a first-person view of the physical environment of a user. The other view, built using Java, shows a close-up view of devices and objects the user may manipulate. These views act as one unified whole by maintaining a client-server model with a central server. Multiple users can attach to the same server to create interactive ubiquitous computing scenarios. We describe how UbiWise looks to researchers and examples of its use as tool for ubiquitous computing research. 17 Pages