Cold , dense water with high salinily sinks as it moves toward the equator . as it is heated it because less dense and rises moving water back toward the north pole .this describs which type of ocean current

The answer is; ocean gyres caused by thermohaline circulation.

Generally, the warm currents from the equator move toward the poles. As they do, they lose heat and become denser. They, therefore, sink to the bottom of the ocean floor and begin moving up the equator again. As the warmer surface waters move towards the poles, the cooler denser waters rise up to replace the moving warmer waters.