Testing is of high importance for optical fibre submarine cable systems since, together with a proper design and a careful definition of technologies, it is the only way to guarantee that the quality, lifetime and reliability performance of an optical fibre submarine cable system shall be met. It is to be recognized that numerous test methods are specific to particular system designs and are therefore proprietary information of the system designer/supplier. However, a common understanding needs to be met between the system designer/supplier and the system purchaser/operator about the general purpose of testing and the meaning of the results. Insofar as they are applicable to optical fibre submarine cable systems, general test methods recommended by the ITU-T should be applied. It should be recognized that these methods may need adaptation to the specific characteristics of optical fibre submarine systems. It should also be recognized that some test methods are specific to optical fibre submarine cable systems and of little or no use elsewhere. The purpose of this Recommendation is to highlight the testing of optical fibre submarine cable systems by listing the main tests applicable to these systems and by describing test methods specific to these systems.