Deep-sea mining (DSM) is the process of removing mineral deposits from the deep ocean floor. The minerals targeted contain metals such as nickel, cobalt, copper and manganese. While experimental and exploratory work is already underway, deep-sea mining has never taken place at a commercial scale.
There are currently three different types of deep-sea habitats, where metal-rich deposits are formed and are targets for deep-sea mining. The first is mining for polymetallic nodules found in abyssal plains. Polymetallic nodules are small, rock-like formations that are made up of metals such as manganese, iron, nickel, copper and cobalt and are found in the dark depths of abyssal plains, which covers 70% of the ocean floor and is one of the largest habitats on Earth. The second is for cobalt and manganese-rich crusts on biodiverse underwater mountains, known as seamounts. The third type is for sulphide deposits found at hydrothermal vents. These vents act like hot springs on the ocean floor, spewing out mineral-rich waters. Of these, polymetallic nodule mining is the main focus of current commercial interest.
Deep-sea mining companies have their eyes on international waters, where the bulk of the ocean’s critical minerals are found. Unlike national waters, which are areas where a country has control over mining, international waters refer to the ocean beyond any nation’s jurisdiction. The Clarion-Clipperton Zone (CCZ) is an area of international water between Hawai‘i and Mexico. It’s around twice the size of India and is composed of abyssal plains that contain the largest known concentration of polymetallic nodules identified to date. As such, it is a major target for deep-sea mining. Deep-sea mining is also being explored within some countries’ national waters, including parts of the Pacific, Indian, Arctic and Atlantic Oceans.
Experts warn of grave environmental, economic and social consequences of mining in the fragile and largely unexplored (over 5000 distinct species have been collected but not yet identified in the CCZ alone) deep-sea ecosystems, as well as the risk of costly liabilities for countries who sponsor deep-sea mining projects in international waters.