The objective of this seminar is to place maritime spaces at the heart of our exchanges. Often considered as mere margins of national territories or extensions of a sovereignty space exercised on land, maritime spaces can also be studied as autonomous spaces. It is also a question of understanding the sea not only as a rupture, an obstacle or a natural barrier, but also as a link, a crossroads of exchange, or even a complex link between distinct socio-cultural groups. The seminar aims to question the relationship between land and sea spaces, the political and geopolitical roles of the seas (affirmation of power, desire to limit and close off maritime spaces) as well as the projects envisaged to protect marine ecosystems that are increasingly fragile and threatened.