With slack from the S shape, the cable can move, flex, and rest on the seabed without snapping or getting pulled too hard. They also bury the cable in shallow water using a plough, which is like a big underwater tractor, for extra protection from anchors and fishing nets. Submarine cables are laid using special cable layer ships, such as the modern René Descartes, operated by Orange Marine. Engineers design these cables to withstand pressure, corrosion, and mechanical stress. These ships follow a carefully mapped route from continent to continent, dropping the cable onto the. Modern submarine cables use fiber-optic technology.