Why are manganese nodules on the seafloor not widely mined?

Manganese nodules are not widely mined primarily due to economic and technological challenges. Currently, the recovery of these nodules from the seafloor is too costly to mount a commercial operation, as they cannot compete with the ready exploitation of high-grade terrestrial deposits. Furthermore, the specific technology required to extract these resources economically has not yet been fully developed.123

Beyond these practical hurdles, there is a general lack of comprehensive knowledge regarding the resource. The legal framework also plays a significant role: minerals on the ocean floor in the International Seabed Area are considered the "common heritage of mankind". Their exploitation is strictly regulated by the International Seabed Authority to ensure that benefits are shared globally, particularly with developing countries. While exploration has occurred, the complex regulatory environment and the need to balance resource extraction with environmental protection have limited commercial activity to date.345