|Frequently Asked Questions
Why is the ocean blue?
No one knows for sure. There are several theories as
to why the ocean is usually blue. Some scientists believe that when sunlight
hits seawater, part of the white light is absorbed and part is reflected.
White light is composed of various shades (all the colors in the rainbow).
Seawater does not absorb blue light, so the blue light is reflected outwards.
Some scientists believe that suspended matter in the sea is responsible
for its blue color.
What causes waves?
Wind is the most common cause of surface waves. The longer
the distance a wind blows, the stronger it is, and the bigger the waves.
As wind blows over the ocean, it tries to pick up some of the water. Because
the surface of the water can not move, it rises. Gravity pulls the wave
back down into the ocean. However, the water now has momentum. Water pressure
from below pushes the water back up, and the cycle starts again.
How far can sunlight penetrate
into the ocean?
Significant sunlight can only penetrate 100 meters freely.
Because seawater is relatively transparent, about 5% of sunlight penetrates
to a depth of 262 feet (80 meters). However, if the water contains significant
amounts of silt, algae or other factors, the penetration depth can be reduced
to 164 feet (50 meters) or less. Learn more about
the ocean light zone.
How many oceans are there in
There is really only one big ocean. One can sail in a
boat in every known "ocean" and "sea", which means they are all connected.
What are the main "oceans" called?
It is generally recognized that there are five main areas
in this one big ocean:
What is a sea?
The Pacific Ocean
The Atlantic Ocean
The Arctic Ocean surrounds the North Pole. It is the
smallest "ocean" with only 5.5 million square miles and 4% of the world's
water. It is frozen all the time, except at its edges.
The Indian Ocean is the third largest area. It covers
about 28 million square miles and holds 20% of the world's water. About
90% of the Indian Ocean is south of the equator.
The Southern Ocean is where you'll find Antarctica
and the South Pole. Some say it is not an "ocean" at all, but the southern
part of three "oceans": the Pacific, Atlantic, and Indian.
A sea is a branch of one of the five "oceans". A sea
is partially enclosed by land. For example, the Indian Ocean is divided
in two by the country of India, forming the Arabian Sea on one side and
the Bay of Bengal on the other.
What are the world's largest
1. The South China Sea
What are the world's largest islands?
2. The Caribbean Sea
3. The Mediterranean Sea
1. Greenland, northern Atlantic
2. New Guinea, southwest Pacific
3. Borneo, southwest Pacific
4. Madagascar, western Indian
5. Baffin Island, northern Atlantic
Why is the ocean salty?
It is salty because it has a lot of salt in it! Salt
is a mineral that is found in soil and rocks, too. Flowing water picks
up some salt and carries it to rivers. Rivers carry it to seas. Since this
has been happening for millions of years, the oceans now have a lot of
salt—about one cup per gallon!
Where is the deepest part of
The deepest place is near the Mariana Islands in the
Pacific. The water is over 36,000 feet deep in the Mariana Trench. That's
over 7 miles deep. Mount Everest is only 6 miles high!
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