In this paper the results of an experimental wireless sensor network application in a coastal shallow water marine environment are presented. The study focuses on the practical aspects of deployment, data gathering and retrieval events. The trial sensor network was used to retrieve temperature and illuminance data from the seabed of Moreton Bay, Australia. The application described possesses features and implements technical solutions that distinguish it from previous deployments. For example, the particular mooring system maintains the buoys horizontal on the water's surface even in strong tidal current conditions, thus enabling reliable communication at 2.4 GHz. In this application, the underwater sensors were wired to surface wireless nodes, and this arrangement led to various difficulties in the network's deployment, maintenance and retrieval phases. For this reason, the knowledge acquired through this experience is presented in this paper to provide insight into, and to further stress, the importance of using fully wireless systems in monitoring applications for the marine environment.