The Strait of Gibraltar has a long tradition of political and scientific uniqueness. Twentieth-century submarine warfare added the ocean’s depth as a new dimension for those wanting to control and understand the Strait. During the Cold War the surveillance of this chokepoint became urgent and entangled with local disputes predating the two-blocs conflict, in particular the sovereignty of Gibraltar for which Spain and the United Kingdom competed. This paper explores a number of transnational research programs on ocean dynamics at the Strait and discovers a network of collaborating researchers who used, and went beyond, international institutions such the International Geophysical Year and NATO. In the process, the Western Mediterranean was constructed as a key maritime place for global ocean circulation, both as a factor to North Atlantic convection and as a model through which to understand it.