Spilled oil in the marine environment significantly changes the conditions of marine biochemistry and poses a major threat to the marine ecosystem and human health, which in recent years has become a key issue in marine chemistry and biological research. Due to the chemical properties of oil and its harmfulness to environment, it is necessary to react immediately and prevent the spread of oil on the water surface when a spill occurs. Through this paper, both theories of the origin of oil are presented, ie the scientific reasons why oil was created organic, ie inorganic. Crude oil is classified on the basis of physical characteristics and chemical composition, variation in price, utility and environmental impact. Oil pollution of the sea refers to oil and its refined products that enter the marine environment in the process of exploitation, refining, storage, transport and use. The spread of an oil slick over the water surface is a complex process that is systematically described by the Ishikawa diagram. An oil slick moves across the surface under the influence of forces acting on every particle in the sea. The development of the Ishikawa diagram describes the causes, sub-causes, sub-sub-causes... to level 5th causes. Consequence, i.e. the problem in this case, in Ishikawa diagram is spreading oil slicks in the sea. Theoretical framework for development of the Ishikawa diagram defined through mathematical equations shows that the spreading of oil slicks in the sea depends on sea pressure, friction force, Coriolis force, buoyancy force, equation of state, tangential stresses due to wind action (wind currents), tidal forces, tension force and diffusion.