Deep-sea mining is the process of exploring the deep seabed and retrieving minerals like cobalt and manganese (used in things like rechargeable batteries, smartphones, and steel), as well as gold, nickel, and rare earth elements. Private companies are designing and testing several technologies to explore and sample wide areas of the ocean floor. However, researchers do not fully understand the consequences of deep-sea mining. These could include the release of sediment plumes that contain toxic heavy metals, which could affect ecosystems and spread to other countries on ocean currents.