>Hot water is less dense and will float on room-temperature water, while cold water is more dense and will sink in room-temperature water.
>Ocean currents affect the temperature by moving hot or cold water from one location to another. The Gulf Stream, for example, moves warm air from the Gulf of Mexico along the eastern coast of the U.S and eventually to the British Isles. As the warm water travels North, it warms the water and air around it.