The ocean appears blue because of the reflecion of the blue color of the sky. On a cloudy, overcast day, the ocean appears gray or very dark.

The ocean currents are constantly moving, and distribute heat and energy around the globe. This helps heat the land and air during winter and cools it during summer.

The Earth's oceans are all connected to one another.

They are:

1. The Pacific Ocean, 64,186,000 sq miles or 103.275.274 km in area, and 15,215 ft or 4637.532 mts deep.
2. The Atlantic Ocean, 33,420,000 sq miles or 53.772.78 km in area, and 12,881 ft or 3926.129 mts deep.
3. The Indian Ocean, 28,350,000 sq miles or 45.615.15 km in area, and 13,002 ft or 3963.01 mts deep.
4. The Arctic Ocean, 5,106,000 sq miles or 8.215.554 km in area, and 3,953 ft or 1204.874 mts deep.
5. The Antartic Ocean 7,848,300 sq miles or 12.627.914.7 km in area, and 16,400 ft or 4998.72 mts deep.

There are also many seas, (smaller branches of an ocean). Seas are often partly enclosed by land. The largest seas are the Mediterranean Sea, the South China Sea, and the Caribbean Sea.

How do we get Waves?

Some of the energy the winds create is transferd to the water. This cause waves on the surface of the ocean (You can duplicate miniature waves by blowing across the surface of a small body of water). This occurs through friction between the air molecules and the water molecules. So light winds cause small waves and stronger winds cause larger waves.

These waves of water do not move horizontally, they only move up and down (a wave does not represent a flow of water). You can see a demonstration of this by watching a floating buoy bob up and down with a wave; it does not, however, move horizontally with the wave.

Tsunamis (tidal waves) are different from surface waves, they are usually caused by underwater earthquakes, volcanic eruptions, or landslides.

Why are the Oceans Salty?

As rain water flows down creeks then rivers it picks up small amounts of mineral salts from the rocks and soil of the streem and river beds. This very-slightly salty water flows into the oceans and seas. The water in the oceans only leaves by evaporating (and freezing in the polar ice), but the salt remains dissolved in the ocean,Salt does not evaporate. So the remaining water gets saltier and saltier through time .

The salt content of ocean water varies. On average one cubic foot of sea water contains approximatly 2.2 pounds of salt. The oceans are about 3.5% salt (by weight). Salinity is generally reported in terms of parts per thousand.

The saltiest water to be found is in the Red Sea and the Persian Gulf, These seas have a high salinity, due to very high evaporation rates and low fresh water.

The least salty seas are in the Artic and Antartic oceans where both the melting ice and a lot of rain dilute the salinity.

What causes the tides?

Tides are the constant riseing and falling 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. Two tides occur each day.

Neap tides are especially weak tides. They occur when the gravitational forces of the Moon and the Sun are perpendicular to one another (with respect to the Earth). Neap tides occur during quarter moons.

Spring tides are especially strong and high tides (they do not have anything to do with the season Spring). These occur when the Sun, Earth, and the Moon are in a line. The gravitational forces of the Moon and the Sun both contribute to the tides. These Spring tides occur when we have a full moon and a new moon.

To see a animation on how the tides rise and fall by the moons gravitational pull click hereThis may take one or two minutes to load.