An increasingly contested space: the Pacific seabed and the actors reshaping it

The Pacific seabed is no longer an empty space between nations. It is becoming one of the most strategically crowded environments in the region. That crowding is producing a qualitatively different strategic environment – one where the risks are generated not by any single actor or activity, but by the interaction between them.

For decades, Australia’s maritime thinking has been shaped by what sits above the surface. Ports, ships and naval platforms have defined how influence and security are understood. But the next contest for influence in the Pacific is increasingly unfolding below it. The key shift is not simply use of the seabed but its simultaneous use for various purposes by many actors with different objectives.

The result is growing density, which is reshaping maritime power. Density is an underappreciated variable in Pacific maritime strategy. Individual activities – such as mining, cable routing, military operations and criminal exploitation – can each be managed within existing frameworks. What cannot be managed within those frameworks is the friction generated when they occupy the same space at the same time.

The Pacific maritime domain has always been vast, but it is no longer sparse. Critical infrastructure, resource extraction, commercial activity, military operations and criminal exploitation are increasingly occupying the same physical environment. These are often analysed separately – fisheries in one policy area, submarine cables in another, seabed minerals in another and transnational crime in yet another. In practice, they are converging on the same space.

That convergence matters because it is occurring where governance capacity is limited and economic pressures are increasing. Illegal, unreported and unregulated fishing remains one of the most persistent sources of economic loss in the region. It removes value from Pacific waters before it can be converted into domestic revenue, weakening financial resilience and reducing resources available for development and state capacity. When that foundation is eroded, governments look for alternative sources of growth.

Increasingly, attention is turning to the seabed. Deep-sea mining is being explored by several Pacific  states as a potential source of long-term revenue. For countries such as Nauru, Kiribati, Tonga and the Cook Islands, seabed minerals represent the possibility of significant economic transformation. But the technology is complex, the vessels are specialised and the financial and logistical systems required are beyond the capacity of most small states.

This creates dependence on external partners that provide financing, infrastructure, and long-term commercial and security arrangements. Once established, these elements become embedded in the wider maritime system, shaping how access is structured and how economic activity is organised. What results is not simply external influence. It is structural embeddedness – a condition where the choices available to Pacific states, and to Australia, are narrowed before any overt contest begins.

In the Pacific, China’s role is often framed in terms of military access or strategic competition, but this overlooks a broader pattern of engagement. Infrastructure and telecommunications projects, policing cooperation, logistics support and development financing collectively form an expanding network of maritime presence. Each initiative can be justified on its own terms, but together they generate a structural position within the region’s maritime economy that influences how access and activity evolve over time.

Submarine cables carry almost all digital communications globally and form the backbone of connectivity across the Indo-Pacific. Their routes are fixed, landing points are limited and repair capacity remains concentrated in a small number of specialised vessels. In an environment of strategic competition, these systems are critical dependencies embedded in the seabed and increasingly exposed to grey-zone risks.

At the same time, activity below the surface is increasing. Military submarines, autonomous underwater vehicles, scientific and commercial survey operations now share the same physical space as cables and prospective mining sites. The underwater domain is becoming more crowded, which changes how it functions.

That congestion isn’t limited to state activity. Semi-submersible trafficking vessels across the Pacific show that organised criminal networks are increasingly operating in this environment, moving across vast distances with limited detection and exploiting the same governance gaps that shape legitimate maritime activity. Their importance lies less in the commodities they carry and more in what they demonstrate: the seabed is becoming accessible to a wider range of actors that are each using it for different purposes, and none these actors is aware of, or accountable for, what the others are doing in the same space. That is the condition existing frameworks are not built to manage.

Policy frameworks haven’t adapted to this shift. Fisheries are treated as a resource issue. Cables sit within telecommunications policy. Deep-sea mining is framed through environmental and economic debate. Maritime crime is handled by border and law enforcement agencies. Military activity is managed by Defence. Each approach is valid, but none fully captures how the system is changing. The gap is not analytical but rather lies in how these domains are governed separately while converging physically. The seabed does not observe those boundaries.

Australia has invested heavily in Pacific partnerships and maritime awareness. That work remains important but is largely designed for a less crowded environment.

The next challenge is to develop frameworks adequate to an increasingly populated seabed – one where the greatest risks will announce themselves not through a single adversary’s action but through the accumulated weight of a system that no one is governing as a whole.