Large artificial water reservoirs are one of the most valuable assets in flood protection. However, the overall volume of a reservoir can decrease over time. This happens mainly because of sediment accumulation, and that alluvia is “eating-up” an otherwise useful volume of water. It is therefore important to know the current volume of sediments accumulated in the reservoir. This way one is able to calculate the useful volume of the reservoir storage capacity, secondly, for assessment of future reservoir operation. The process of obtaining relevant data for this is normally partially automated but nevertheless, it is arduous, extremely time-consuming, and may be dangerous. To overcome those problems we have developed an unmanned vessel, which is able to perform the work much faster and easier. The vessel is a fully unmanned, integrated, nonetheless it is still under development (working prototype 1E), but it can be still easily used in its current state, albeit with some minor limitations.