What is the primary cause of ocean currents?

The primary cause of ocean currents is largely attributed to wind patterns and the Earth's rotation. Winds blowing across the ocean's surface impart energy to the water, creating surface currents. Additionally, the rotation of the Earth influences these currents through the Coriolis effect, which causes moving water to turn and twist as it flows, leading to the characteristic circular patterns known as gyres.

While temperature differences in water do play a role in generating currents—particularly deep ocean currents and their thermohaline circulation—the initial and most visible drivers of surface currents are wind and the Earth's rotation. The gravitational pull of the moon affects tides more than currents, and solar radiation influences water temperature, which in turn can affect current patterns. However, neither of these are the primary causes of the large-scale ocean currents observed in major ocean basins.