Seabed mining is the latest threat facing the oceans.

If seabed miners are given the go-ahead to plunder the ocean floor, it could be devastating for marine life.

Seabed mining is a new threat facing the oceans. If given the go-ahead, seabed miners could devastate marine life as they dredge the seabed to extract metals and minerals. This is in addition to the pressures already facing the oceans from overfishing, the climate crisis and pollution.

So far, there is no commercial seabed mining anywhere in the world. But here in Aotearoa, one company, Trans-Tasman Resources, is applying to get started in the South Taranaki Bight, and other companies are desperate to start deep sea mining in the Pacific.

What is seabed mining?

Seabed mining involves dredging up the seafloor to extract metals and minerals. Then unwanted materials are dumped back into the sea, smothering the surrounding area with a sediment plume, like a dust cloud, which will travel for kilometres. Both the dredging and the dumping are likely to cause environmental damage.

Some of the deep sea areas that are being targeted for mining also support some of the most unique and least understood biodiversity on the planet.

Deep sea mining is seabed mining

The terms seabed mining and deep sea mining are two sides of the same coin. Both mean plundering the ocean floor to extract minerals and metals, leaving devastation in place of diversity. Typically, the term deep sea mining refers to mining polymetalic nodules from the seafloor of the deep sea. Seabed mining typically refers to shallower mining where the sandy seafloor is sucked to the surface in large quantities where minerals are extracted from it.

How does seabed mining work?

Seabed mining in the South Taranaki Bight would involve a suction pump like a massive vacuum cleaner that sucks up sand from the seabed to a dredger ship above. The sand would be sorted while still at sea, with the minerals or metals extracted and exported offshore. Whatever is left would be dumped back into the water, smothering the surrounding area with the sediment plume.

What are the risks of seabed mining?

Seabed mining is a relatively new and experimental technique. Much of the science around its environmental impacts is incomplete.

We know less about the deep sea than about the surface of the moon. In fact, it was only in July 2024 that “dark oxygen” was discovered. Strange potato-shaped metallic lumps – polymetallic nodules – are producing oxygen on the deep sea floor – and companies want to mine them.

We don’t yet know the full significance of this discovery, but we do know now that these nodules have a role within the deep sea ecosystem. And it highlights how damaging it could be to destroy an ecosystem we barely understand, and yet depend on.

Read more: What the discovery of dark oxygen means for seabed mining

Seabed mining would be devastating for the fragile ecosystems, wildlife and environment. Below are just some of the risks seabed mining would pose:

The scariest thing is we don’t yet know the full consequences that seabed mining would have. If approved, Trans-Tasman Resources would be the first large-scale seabed mining project in the world.

What is the long-term impact of seabed mining?

Apart from the direct impact of seabed mining, there could also be knock-on effects that can take longer to recognise.

Look at this image here from the deep sea off the coast of South Carolina. It’s the chilling aftermath of the world’s first-ever deep sea mining site. What makes this really shocking is it was mined in 1970, and yet it looks as though it happened yesterday.

Fifty years have passed since the seabed was disrupted by a deep sea mining test, and yet, there is no sign of recovery. What was once a vibrant marine ecosystem now resembles a barren wasteland, a testament to the destructive greed of industry. Seabed mining risks causing serious and irreversible damage to oceans.

Seabed mining is the latest form of colonialism

Seabed mining is just the latest form of colonialism. Once again companies are lining up to engage in another destructive, extractive industry that will harm Indigenous Peoples. For many Indigenous groups, especially those in the Pacific, the sea has deep cultural significance and is important to their livelihoods and food security. They know that harming the ocean and the creatures that live in it also harms their communities. They know that people are not separate from the environment; instead, they are a part of it, and their well-being is linked to it.

What is the threat of seabed mining in Aotearoa?

Seabed mining is an immediate threat in Aotearoa. Australian-owned Trans-Tasman Resources (TTR) has fought for more than 10 years to start seabed mining off the coast of Patea in the South Taranaki Bight.

Find out more: Seabed mining in Aotearoa

Deep dive: Who are Trans-Tasman Resources?

If this goes ahead, it would be the largest project of its kind anywhere: an underwater open-cast mine that would pull millions of tonnes of iron sand from a 6