The sea has long been envisioned as antithetical to land, and therefore geography and the state. The Global Network of Navies (GNoN) is a Pentagon-led program that seeks to extend state power over the seas by cultivating naval interoperability. Interoperability has been a source of American military might since World War 2, but took on heightened importance after the Cold War. In this paper, I make three related arguments. First, I argue that the GNoN is an attempt to produce ocean space within a U.S.-led, but ultimately transnational, state assemblage. Second, I argue that this project relies on the materiality of the sea to affectively nudge forward transnational cooperation. Third, I argue that this reliance on the materiality of the sea is paradoxical, as the GNoN attempts (and ultimately fails) to dematerialize ocean space into abstract network ontology. To make these arguments, I first theorize interoperability through assemblage, highlighting how a transnational state assemblage emerges that works through, but is not reducible to, individual states. I then trace a genealogy of maritime space, showing how maritime space was assembled with U.S. naval technologies and strategies in the nineteenth and twentieth centuries, culminating in the GNoN. Next, I examine the technical challenges of naval interoperability, focusing on C4ISR technologies. The sea's materially limits flows of data that have become synonymous with today's warfighting. Many of the Pentagon's potential partners lack the high-end technology required to be interoperable with the U.S. The C4ISR technology that is therefore distributed to partners is both technical and political; the U.S. remains central to data fusion and distribution. I then return to the sea itself, showing how the GNoN tries to dematerialize the sea but ultimately runs aground on the shoals of materiality. What remains is a smaller, fragmented spatiality that remains oriented around specific seas.