The water in the ocean is moving constantly. On the surface the water moving forms the waves. Below the surface the water moves in great currents.
The ocean waves are caused by the wind moving across the surface of the sea or the ocean. The friction between the air with the water causes energy transference from the wind to the water and the water moves causing the wave.
An ocean current is a continuous flow of water in the ocean. Some currents are surface currents while other currents are much deeper flowing hundreds of feet below the surface of the water.
Surface currents are usually caused by the wind. As the wind changes, the current may change as well. Currents are also influenced by the rotation of the Earth called the Coriolis effect. This causes currents to flow clockwise in the northern hemisphere and counter clockwise in the southern hemisphere.
Deep ocean currents are caused by a number of things including changes in the temperature, salinity (how salty the water is), and density of the water.
One other factor impacting ocean currents is the gravitational pull of the Moon and the Sun.
Do currents impact the climate?
Ocean currents can have a significant impact on climate. In some areas warm water is moved from the equator to a colder region causing the region to be warmer.
One example of this is the Gulfstream current. It pulls warm water from the equator to the coast of Western Europe. As a result, areas such as the United Kingdom are typically much warmer than areas at the same northern latitude in North America.
Tides are the daily rise and fall of the water level in oceans and seas. They are caused by the gravitational forces of the Moon and the Sun. The high tide is when the water reaches its maximum level and the low tide when it falls.