If one uses Facebook, Facetime, Skype, Netflix, or any application of the internet internationally, a submarine cable is involved. Fibre optic cables bind the world together from governments, banks, shipping, airlines and other major logistic industries to homes and personal electronic devices. Server farms maintained by major telecom and content companies allow vast amounts of data to be stored and retrieved from thecloud. Not often appreciated is the fact that these server locations worldwide are connected by submarine fibre optic cables. In this sense, thecloudis beneath the sea. While submarine communication cables have been in steady use since 1850, their preeminent place in the modern world has never been as dominant and personal as now. Since 1884, this critical international infrastructure has rested upon international treaties, now reflected in universally accepted provisions of the 1982 United Nations Convention on the Law of the Sea (unclos) that provides for freedoms to lay and maintain international submarine cables. Recently, calls have mounted in the context of marine biodiversity beyond national jurisdiction (bbnj) for centralized control of submarine cables and for express orde factodiminishment of the freedoms related to them that have served the world’s peoples for so long. This monograph examines the time proven importance of the existing international treaties, the largely peer review science on the environmental interaction of submarine cables with high seas environments, and the current submarine cable issues in the context of thebbnjdebates.