This paper presents a new low-cost autonomous underwater vehicle (AUV) for inspection of water-filled tunnels. Deployment in flowing water tunnels and later retrieval at the tunnel exit produces a two-dimensional height vs. time plot of the tunnel, which can be compared to tunnel schematics. The resultant contour data is useful for maintenance planning and tunnel assessment in terms of internal clogging. This paper presents a proof-of-concept for traversing water filled tunnels by using water flow and variable buoyancy. Empirical data is collected in a scaled down version of one specific water supply tunnel in Norway.
