How was the sea represented during the Middle Ages? The sea is often represented in medieval art as the natural backdrop to an historical or religious scene, where it might carry a symbolic dimension. It is also depicted in scientific works dealing with the elements and nature, and finally, in diverse forms of cartography. The representation of the extent and shape of the world’s seas and oceans thus reflects simultaneously general geographical knowledge as well as the experience of the reality of that space. Consequently, this chapter deals with three main aspects of the representation of the sea in medieval art and cartography: the iconography of the sea in the visual art of the Mediterranean, modes of mapping the seas and oceans in Europe and the Islamic world, and finally other perspectives on the sea in East Asia within the history of trans-Eurasian interactions