Since Antiquity, man has been well aware of the benefits brought by mastery of the sea, and states have continuously sought for ways to exploit it to exercise their power. The sea is an area in which states can affirm their sovereignty and exert their economic strength and influence. Yet it is also an area of risks. Globalisation of trade, the new geopolitical scene and the proliferation of threats in today’s world are such that mastery of the sea is an issue that calls for strong French defence within a European framework.