This essay is part of the Volumetric Sovereignty forum.

The South China Sea is politically contested from its surface to its bed. China, Taiwan, Malaysia, Vietnam, the Philippines, and Brunei all make claims on the volume of this sea — known variously (the list is not exhaustive) as “the South Sea (南海),” “the East Sea (Biển Đông),” “the Luzon Sea/the Philippine Sea,” and “the Natuna Sea.” Sweeping through the depths of this sea (and particularly through the Luzon Strait, between Taiwan and the Philippines) move oceanic phenomena known as “internal waves” (Alford et al. 2015), enormous waves that travel underwater, that manifest at the interface between layers of water stratified by density — stratification that is driven by temperature and/or salinity differentials. Picture an underwater wave 150 meters tall, its upper boundary traveling just below an undulating stratum of lighter water, whose sea-meets-air surface — home to fishing vessels, research ships, and oilrigs — betrays only a hint of the massive movement beneath. Traces of internal waves, mostly indiscernible to the untrained human eye from the surface, become readable via synthetic aperture radar images from satellites and via virtual reconstructions from underwater sounding data, indicating that such volumes come into representation largely through the tools of nation-state, military, and computer science projects and funding.

What sorts of sovereignties do internal waves move through? Who generates and makes use of scientific accountings and imaginings of these mobile volumes? For what purposes? One answer might be the People’s Republic of China, already constructing artificial islands in a bid to gain surface territory in the Sea, territory that would include both islands and their adjacent waters (a bid that an international tribunal in the Hague, finding in favor of Philippine contestation, has declared void of historical or legal foundation). Through the National Institute for South China Sea Studies in Hainan province, the People’s Republic is planning an underwater observation network aimed at surveying undersea mountains. Spokespeople for the institute suggest that “[y]ou could say to some extent [the research] helps protect our sovereignty claim, but actually the goal of these projects’ designs is not mainly one to show the country’s claim” (Jennings 2017) — though other powers in the region presume that Chinese knowledge of the seabed and of the internal waves that roll over it will be used to shore up the People’s Republic’s access to and claims on deep-sea resources, particularly natural gas hydrate. Fishing industries based in Taiwan and the Philippines, meanwhile, which have fought over fishing rights in the Luzon Strait, may find knowledge of internal waves informative for tracking the location of fish populations, since these waves shape the travel of oceangoing nutrients, guiding patterns of organisms’ feeding and breeding (Moore and Lien 2007 report, for example, that pilot whales forage while following internal waves). Oil and gas companies — of many nationalities — also stand to profit from knowledge about internal waves in the Sea: “Internal waves act on offshore structures, resulting in large amplitude motions which brings serious harm to the deep-sea oil and gas engineering” (Fang and Duan 2014: 549; see also Dickinson et al. 2012: 231). Internal waves also have effects on the submarine sound world, perhaps, in the context of acidifying seas, in such a way as to amplify underwater noise (Rouseff and Tang 2010; see also Reeder et al 2016), which can impact the navigation of submarines and the travel of sea life.

So, while internal waves are not themselves the objects of three-dimensional sovereign claims, knowledge about them is generated by scientists who are able to navigate access to these scrolling volumes — access that is shaped by ocean governance regimes (in which nation-states have rights over the waters of their Exclusive Economic Zones [EEZs] and the seabed located on their adjacent continental shelves; the International Seabed Authority has jurisdiction over the seabed outside EEZs; and the High Seas [the water column outside EEZs] are subject to no such authority). U.S. and Taiwan-based researchers, for example, funded by the Taiwan National Science Council, in collaboration with the United States Office of Naval Research, often gather their mooring data at sea sites controlled and claimed by Taiwan — though they are then able to reconstruct internal wave processes unfolding within Chinese-claimed waters (see figure 1). One might say that such reconstruction — in, for example, the virtual worlds of computer models — places the knowledge object of the wave under the sovereignty of science (made possible, to be sure, by national funding agencies and infrastructures).

Cross section of South China Sea showing the travel of internal wave volumes. Figure 3d from Alford et al. 2015.

But such objects may then become looped back into more traditional political sovereign claims and contests — with waves inferred through reflection and diffraction offering a kind of remote sensing that could potentially permit states, without directly moving into other states’ sovereignty, to gather at-a-distance knowledge about volumetric territories beyond their own. Internal waves themselves, meanwhile, can produce turbulence between the seabed and the water column, mixing up what belongs to which depth-calibrated and contested sovereignty. The range of venues in which findings about internal waves is published — which includes such disparate journals as The Journal of Petroleum Technology, Marine Mammal Science, and Coral Reefs — also points to the many possible communities and polities (with different degrees of power and influence) that may be invested in these traveling volumes, known through overlapping, mutually reinforcing as well as diffracting sovereignties of science, commerce, the state, and the international.


Alford M, et al (2015) The formation and fate of internal waves in the South China Sea. Nature 521: 65–69.
Dickinson J, K Ware, S Cosham, and B Murphy. 2012. Slope Failure and Canyon Development Along the Northern South China Sea Margin. In Submarine Mass Movements and Their Consequences: 5th International Symposium, edited by Yasuhiro Yamada, Kiichiro Kawamura, Ken Ikehara, Yujiro Ogawa, Roger Urgeles, David Mosher, Jason Chaytor, Michael Strasser. 223-232. Springer.
Fang, Huacan and Menglan Duan. 2014. Offshore Operation Facilities: Equipment and Procedures. Amsterdam: Petroleum Industry Press.
Jennings R (2015) Common threat to cool dispute between Taiwan and the Philippines. Forbes, June 7, Available here.
Moore, S.E. and R-C Lien (2007) Pilot whales follow internal solitary waves in the South China Sea. Marine Mammal Science 23(1): 193-196.
Reeder B, A Chang, C Chen, and Y Yang (2016) Acoustic propagation in the South China Sea: Internal waves and sand dunes. Journal of the Acoustical Society of America 140(4):3013-3013
Rouseff D and Tang D. (2010). “Internal waves as a proposed mechanism for increasing ambient noise in an increasingly acidic ocean,” Journal of the Acoustical Society of America, vol. 127, no. 6, pp. EL235–EL239, 2010.
Xu B (2014) South China Sea Tensions. Council on Foreign Relations, May 14: Available here.