A gyre, also known as an ocean gyre, is a large system of circular ocean currents formed by global wind patterns and forces created by Earth’s rotation.

The movement of the world’s major ocean gyres helps drive the “ocean conveyor belt.” The ocean conveyor belt circulates ocean water around the entire planet. Also known as thermohaline circulation, the ocean conveyor belt is essential for regulating temperature, salinity and nutrient flow throughout the ocean.

Three forces cause the circulation of a gyre: global wind patterns, Earth’s rotation, and Earth’s landmasses. Wind drags on the ocean surface, causing water to move in the direction the wind is blowing.

More Info: nationalgeographic.org