Castle Peak and Black Point Power Stations are adopting the sea water as a coolant to main condenser to condensate the low-pressure steam for water recycle. The cooling water culvert is underground caisson design with approx. 300m located in offshore and approx. 2000m in onshore. The common industrial inspection method is visual inspection by divers with limitations of culvert depth, length, breathing gas, water quality and station operation condition etc. To eliminate exposure to hazards and avoid the high-risk job in the confined space, CLP has rethought the working processes and applied the current state of art technology of Remotely Operated Vehicle (ROV) equipped with video camera, lights and sonars etc. as a longer-term solution for cooling water culvert surveys. These measures enable the inspection of small and hard to reach areas, enable inspection on both wet and dry condition, reduce maintenance cost, improve the cooling water supply reliability and plant integrity.