Polymetallic nodules, also known as manganese nodules, are spherical or irregular concretions found in deep-sea sediments, primarily on abyssal plains. Their composition typically includes significant amounts of manganese, iron, nickel, copper, and cobalt. Cobalt-rich crusts are found on the flanks of seamounts and oceanic ridges, formed by the precipitation of metals from seawater onto the substrate. These crusts are particularly rich in cobalt, but also contain manganese, nickel, copper, and platinum. Hydrothermal vents, often found along mid-ocean ridges, release superheated, mineral-rich fluids from the Earth's crust. As these fluids mix with cold seawater, dissolved metals precipitate out, forming massive sulfide deposits that can contain copper, zinc, lead, gold, silver, and other valuable elements.

Fisheries are the backbone of marine biological resources, providing a significant portion of the world's animal protein. Overfishing and unsustainable practices pose major threats to these stocks. Aquaculture is the farming of aquatic organisms, including fish, crustaceans, mollusks, and aquatic plants. It is increasingly important for meeting global seafood demand and reducing pressure on wild stocks. Marine biotechnology explores the potential of marine organisms for novel applications. This includes the discovery of new drugs (e.g., anti-cancer agents from sponges), enzymes for industrial processes, and biomaterials. The biodiversity of marine ecosystems is essential for maintaining these resources.