The least salty seas are in the polar regions, where both melting polar ice and a lot of rain dilute the salinity. The Earth's oceans are all connected to one another. The largest seas are the South China Sea, the Caribbean Sea, and the Mediterranean Sea. The wind transfers some of its energy to the water, through friction between the air molecules and the water molecules. You can make your own miniature waves by blowing across the surface of a pan of water.
Tides are periodic rises and falls of large bodies of water.
Tides are caused by the gravitational interaction between the Earth and the Moon. The gravitational attraction of the moon causes the oceans to bulge out in the direction of the moon. Since the earth is rotating while this is happening, two tides occur each day. Isaac Newton was the first person to explain tides scientifically. For information on spring and neap tides, click here .