Sea Level is not uniform throughout the world
Ocean currents close to sea level are able to raise or lower the ocean’s surface. This creates large hills and valleys across the top of the water.
This animation shows how ocean currents move clockwise around the so-called “Caribbean Hill”. The red areas visible here are up to 1.4 meters higher than normal sea level. Further north, currents circle through the “Labrador Sea Valley”, a large depression through which the water flows in a counter-clockwise direction (blue). The structure of these eddies determines the speed of the currents that pass 100 meters below them. Smaller vortexes are also clearly visible, which result from instabilities in larger currents, such as the Gulf Stream, or from interactions between currents and winds or the ocean floor.