We present an interface for controlling mobile robots that combines aspects of graphical trajectory specification and state-based programming. This work is motivated by common tasks executed by our underwater vehicles, although we illustrate a mode of interaction that is applicable to mobile robotics in general. The key aspect of our approach is to provide an intuitive linkage between the graphical visualization of regions of interest in the environment, and activities relevant to these regions. In addition to introducing this novel programming paradigm, we also describe the associated system architecture developed on-board our amphibious robot. We then present a user interaction study that illustrates the benefits in usability of our graphical interface, compared to conventionally established programming techniques.