Density Currents

Like air, water that is more dense sinks. This helps create currents deep in the ocean as water flows from areas of high density to areas of low density. A density current is the vertical movement of water caused by differences in density.

Surface Currents

Ocean currents flow at different depths in the ocean. You have learned that density currents move water downward. They carry water from the surface to deeper parts of the ocean.

Surface current is a wind-driven current that carries ocean water horizontally across the ocean's surface. As wind blows over ocean water, it transfers energy to the water. The moving air particles drag on the surface of the water and cause the top portion of the ocean to move.