HiSCS successfully accomplished in November 2018 a very demanding underwater inspection in Al-Shuqaiq Power Plant & Desalination facilities in Jizan province, Kingdom of Saudi Arabia. The Technical Authority of Al Shuqaiq Saline Water Conversion Company (SqWEC) assigned our staff to identify the current defects in the structure (inside and outside) by performing underwater inspection, non destructive testing (NDT) including life-cycle cost analysis, remedies and solutions to rehabilitation by providing a solid conclusion related with the operational efficiency of the tank. We would like to point out that the inspection took place under fully operative tank (5 pumps x 6.250 m3/h) with a water flow about 25.000m3/h under a very aggressive environment (chorinated water), thus, safety was our primary concern. The communication with the divers (fully certified) was achieved using underwater CCTV and a state of the art diving apparatus.