For the 2007/08 Defeating the Weed Menace program (DWM), we proposed to build and test a prototype robotic aircraft and surveillance system to detect aquatic weeds in inaccessible habitats. The know-how and technology is not new: we have been working on such systems for the aerospace industry for over a decade. However, a new application of the technology and the different test environment meant we had to devise new technologies and approaches.