How do ocean currents work?

Welcome! I'm excited to help you explore how the world's oceans stay in constant motion.

To kick off, what brings you to learning about ocean currents today, and how comfortable are you already with general earth science concepts like water density or Earth's rotation?

Learning for school or work, and I have a basic understanding of density and rotation.

Your path

Deep Currents: Thermohaline Circulation

Global Impact & Climate Regulation

Awesome! Having that background in density and rotation will make this super intuitive.

At its simplest, an ocean current is a continuous, directed movement of seawater that flows across the globe like a giant, river-like system within the ocean. Rather than staying still, water is constantly moving from one region to another.

Scientists divide these movements into two primary layers: and . Surface currents make up just the top 10% of the ocean's water, driven mainly by global winds and coastlines. The remaining 90% is in the deep ocean, where water moves much slower due to density variations.

Continue to surface currents and wind

Let's dive right into surface currents! As wind blows across the open ocean, friction drags the top layers of water along with it, creating massive surface streams.

However, water doesn't move in a straight line with the wind. Because the Earth is constantly spinning, moving objects—including ocean water—are deflected. This natural curvature is known as the .

Earth counterclockwise rotation and Coriolis deflection of trajectories curving right in the Northern Hemisphere and left in the Southern Hemisphere.

I've generated a simple visualization above to show how Earth's rotation bends the path of moving water. In the Northern Hemisphere, water gets deflected to the right, while in the Southern Hemisphere, it gets pushed to the left.