A radio linked Echo Sounder was developed for baitboats in 1994 to aid discovery of features important to seeking out elusive fish. The equipment has been refined over the years to provide detailed images of the bottom of ponds, lakes, rivers and sea beds. Depths of up to 100m can be measured and there is fundamentally little limitation to the radio ranges which can be employed. Fulcrum Designs has developed castable echo sounders and worked on tidal height measuring sea buoys for establishing safe navigation paths for shipping. More recently a mapping system utilising echo sounding equipment and GPS was developed for Cambridge University to monitor silt build-up in a river system. Work on side scan sonar systems is ongoing as is passive imaging - using the sound already present underwater to create detailed images. 3D mapping of waters (bathymetry) is an area of particular interest and the imminent arrival of the European Gallileo satellite navigation network will bring about much higher resolution capabilities for this and other applications.