The fields of land robotics and aerobots are developing ever more rapidly due to accessible low-cost technology, however the same cannot be quite said for marine robotics, as practical underwater vessels continue to stay unaffordable. In contrast, the changes of coastal ecosystems have never been as topical which shows the need for systems designed to handle monitoring and control of these regions. For this purpose we've developed a low-cost prototype of an underwater remote-controlled vehicle (ROV) with included stabilization functions. We based our system on web and gaming technology to develop a mobile control app and the embedded system for vessel control. The final vessel is a coastal ROV intended for low depth monitoring and serves as a case study on the topic and consolidates information for easier vehicle construction. The system was tested on three different locations and iteratively improved as shortcomings were found. We conclude the thesis by presenting the final set of improvements for future vessel construction.