Oceans make up 71% of the surface of our planet, and they are crucial to maintaining the balance of the planet's chemical and biological systems. Human activity has a negative impact on marine life and health because it causes harmful practices, health risks for humans, and fisheries that are hampered by poor seawater quality. Marine pollutants, which include, can harm both humans and animals in a number of different ways. Heavy metals from industrial activity may be carried to surrounding rivers and lakes, harming the fish that live there and, ultimately, people who eat fish. Heavy metallic poisoning is also carcinogenic and can cause congenital defects that cause delayed improvement. Plastic wastes, agricultural runoff, oil spills, metallic and radioactive wastes, oceanic dumping, and municipal and industrial waste are the most significant marine pollution pollutants. Sewage from inland cities and industries can be discharged directly into the sea, which causes eutrophication, deoxygenation, foul deposits, toxic residues, and decreased salinity.

Crude oil from tankers, offshore platforms, drilling rigs, and wells, as well as refined petroleum or any other oil and waste trash, are the main sources of oil spills into the oceans or coastal waterways. The problems with marine pollution are widespread and complicated by oil spills that are combined with sewage from metropolitan areas, silt, plastics, pesticides, and sneaky hazardous substances. Fisheries are severely risked by waste from ships' discharged petroleum and oil refineries. Oils contain hydrocarbons that are absorbed into marine animals' bodily tissues. When a guy eats fish from oil-polluted sea water, it might harm his liver and kidneys and cause respiratory problems. The main and most prevalent pollutant in marine water bodies is plastic waste; many sea creatures accidentally eat flotsam because it frequently resembles their natural prey. When plastic waste is bulky or tangled, it is challenging for animals to pass and may permanently lodge in their digestive tracts, obstructing the passage of food and resulting in starvation or infection.

Metallic and chemical elements are hazardous or poisonous, and at low concentrations, they have a relatively high density. The water contains elements such as cadmium, arsenic, lead, and others. These metallic wastes may naturally infiltrate the marine environment by atmospheric weathering, river discharges, and weathering of the earth's crust. Antifouling paint used on boat bottoms has been identified as a significant source of heavy metals in the environment. Many species of aquatic ecosystem species are susceptible to these harmful metals penetrating their tissues. These fish will harm our neurological system, kidneys, brain, respiratory system, and even cause our death if we eat them. Nuclear and thermal power facilities are the two main contributors to thermal marine pollution. The sensitivity of marine species to temperature fluctuations is very high. Premature fish migration, spawning, a shortage of oxygen, or the death of marine life are all effects of high temperatures. Ecosystems in the maritime environment can be disturbed by the buildup of unstable heat caused by human activity. Radioactive substances are released into the water as a result of nuclear weapon testing, nuclear reactor operating, intentional and unintentional direct releases, subsurface nuclear explosion leakage, and industrial nuclear energy use. Ion-exchange techniques, radionuclide precipitation, and other methods can be used to eliminate or reduce these pollutants. Plants use the radioactive contaminants in sea water that they consume during photosynthesis as a medium for their own radioactivity.