Deep currents are primarily caused by differences in the density of the water, which in turn are related to variations in temperature and salinity. As water gets colder, it becomes more dense and tends to sink towards the bottom, while warmer water is less dense and tends to rise towards the surface. Similarly, when water is saltier it is more dense and tends to sink, whereas less salty water rises. These density differences set up circulation patterns in the ocean, with colder, denser water sinking in some areas and warmer, less dense water rising in others, creating deep currents. Wind patterns can also influence the direction and strength of these currents, but they don't directly cause them.
