This chapter analyzes the shrinking domain of the high seas – taking place as a result of encroachment of continental shelf claims under the UN Convention on the Law of the Sea – and what that portends for the governance both of regional hot spots, such as the South China Sea and the Arctic, and of the Internet, due in part to the expanding web of submarine cables. The chapter begins by exploring how oceanic governance has been shaped by such forces as advancing technology, multipolar politics, and resource scarcity. It next investigates the evolution of the law of the sea from its Roman Law origins to the 1994 New York Amendments of the Third United Nations Convention on the Law of the Sea, with special attention paid to the growth of the territorial seas. It then analyzes the recent spate of continental shelf claims brought to the Commission on the Limits of the Continental Shelf and their impact on the governance regimes applicable to offshore resources, using the Arctic, Antarctic, and South China Seas as illustrative examples. Finally, the chapter applies lessons, such as governance best practices in the form of minilateral norm building from the Arctic Council, to cyberspace.