Visual inspection of a seawater inlet tunnel which feeds West Lakes, South Australia has been executed by AUS-ROV special operations unit. A crane was met on site to lift the 6.5t concrete lid for access to the tunnel. AUS-ROV deployed the LBV300/4 full fibre optic system with 750m of tether on hand winch. The ROV Pilot then 'flew' the ROV to the offshore intake riser 700m seaward of the access shaft. Additional 1080 Lumen LED external lights and the ROV's high resolution camera resulted in quality video footage for identifying in fine detail the current condition of the internal surface of the 3.5m diameter tunnel. This was the first inspection carried out in 36 years and the client was pleased the structural integrity remains un-compromised. Further to this AUS-ROV Environmental Scientist Adrian Jahnke identified several fish species inhabiting the tunnel, concluding that this water asset not only provides clean seawater to West Lakes tidal ecosystem but a safe habitat for fish to occupy.