Ocean, in classical Greek mythology, was the Titan Lord of the River Ocean, the great river encircling the earth. His wife Tethys was also a Titan. His daughters were the Oceanids, the nymphs of the great river. His sons were the gods of all rivers of the earth.

They who do not feast here anymore
have cast their empty shells to the tide.
Waxing and waning, filled by the cries
of sea birds they sink.
There dwells the wooden maid.
Salt has eaten her painted face;
her flesh laid bare, she smiles still.
Their souls shall find no rest upon the waves.

The cosmology of the ancient Greeks contained a river flowing around the outer rim of the world, the domain of the god Oceanus. As the European worldview stretched out beyond the Pillars of Hercules, it became more and more apparent that this "river" was a lot larger than the Mediterranean Sea, than the "known world".

Various regions of the World Ocean, separated by continents or climactic barriers such as the Equator, have their different characters. 1Geographers occasionally divide the two largest oceans at the Equator, as these bodies of water have completely different characters between the Northern and Southern Hemispheres. The definition of particular oceans is controlled by the International Hydrographic Organization, at least for its member nations.

I remember the last time I felt the ocean. It was at Port Isabel, near Padre Island, the week after spring break. The beach had a hangover: crumpled beer cans and cigarette butts, candy wrappers and used condoms. Herring gulls squabbled over choice bits of trash and cried as they wheeled in the sky. The sun was sulking under a blanket of clouds. An unseasonably chilly wind, greasy with salt, blew fitfully across the waves.

The sea spread out to the horizon, rippling like a vast sheet of gray-green satin. The easy roll of the distant swells turned to a surge of foam at the shoreline. The whispering roar of the waves was calling me, pulling my blood as the moon pulls the tide.

I found a clear spot of sand and stripped down to my swimsuit. The wind knotted my skin with goosebumps. I left my sneakers on; the sand was full of hidden fish hooks.

I crossed the beach and waded in, shivering and wincing at the first cold bite of salt on my legs. The current tugged at my ankles. I'd been warned about the undertow; it had dragged under dozens of unwary swimmers. I imagined the victims being pulled down, down into the dark water to become a feast for deep-sea crabs. But today, the undertow was no watery mugger; it was insistent but gentle, almost playful, like a man pulling his lover behind a tree for a kiss. I splashed out into the waves until my toes could barely find the sandy bottom.

I felt a sudden thrill of fear as the swell lifted me as though I were a sliver of driftwood. This was no polite suburban swimming pool. This water was powerful. It wasn't just the force of sheer mass that I felt. Perhaps what I sensed was the kinetic energy of the rolling molecules, the innate force of the wet, heavy children of gases joined in explosive union. Perhaps what I felt came from chemical instinct, the miniature sea in my own veins faltering in the vastness of its ancient birthplace.

After a few minutes, the surges no longer frightened me. The rising, falling swell was the steady breathing of a sleeping creature. The rhythm lulled me, and I lay back in the water and let myself float.

I closed my eyes and let my mind drift. My thoughts left my body and spiraled up, up into the sky, through the misty sheets of clouds into outer space. I imagined I could see the earth spreading below me, nothing of human civilization visible. The sea wrapped the planet like a blue amoeba that had flattened itself around a grain of sand. The sea was moving, pulsing in slow, millennial currents around the globe.

I realized that the sea itself is alive, not just a soup of fish and salt and seaweed, but truly alive. All living things within it, from delicate crystalline plankton to hardy killer whales, are part of a vast, liquid body. The ocean's organisms eat and breed and die to be reabsorbed into the system, life and death locked in a perpetual embrace, just like the cells in my own body.

I had never seen myself as anything but an individual before, but now I realized that I, too, was a cell in the salty blood. And someday I would be gone, broken down into nitrogen and carbon and water, nothing of my essence left but a few genes in future generations of cells.

I felt myself drift away farther into outer space until the Earth looked like a fist-sized white and azure jewel hanging against the blackness. I turned my face toward the heat of the sun. It was swollen, shining the wrong color, pregnant with disaster.

Then it burst, a shell of flame and shock ripping out across space. The fire tore across the Earth, tearing off its living skin, shattering its rocky bones.

I thought I could hear the beautiful blue creature scream as it exploded into cosmic steam.


I woke with a start, shaking. I was so cold I couldn't feel my feet. My skin was white against the dark water. I swam back to shore, my arms and legs weak against the waves. I staggered onto the beach and found my towel and clothes. After I dried off and dressed, I jogged along the beach to coax the blood back into my chilled limbs.

I knew I couldn't go back into the water without courting hypothermia, but I didn't want to leave. So I spent the rest of the day searching for shells in the wet gray sand. The clouds broke in the late afternoon, and I hiked to the jetty to watch the sundown show of brilliant purples and delicate pinks and oranges.

After the horizon had faded to the blackest blue, the real show began. The night tide was thick with phosphorescent plankton that flashed in green alarm at any disturbance. Every crashing wave sent up a spray of ghostly fireworks. Glowing sea foam oozed like lava in the crevices of the jagged black rocks.

Finally, my eyes would hardly stay open, and I started to shiver in the night breeze. I turned away from the jetty, trudged back down the road, through the dingy trailer park to a rickety beach shack in which even the plastic had rusted. I drew a tub of hot, clear, uninteresting water, poured in perfumed bubble bath as faint compensation, and washed the sea from my skin and hair.

But it could not be washed from my mind. As I lay in my bed that night, I could still feel my body rise and fall with the waves, the sensation like phantom pain from an amputated limb.

Approximately 4,000 mya, conditions on the planet earth were insufficient for the support of life. The necessary element that was missing from the composition of the planet was a hydrosphere: a system of oceans covering the surface. A process of cooling would need to take place so that water vapor could condense into rain and form permanent accumulations of liquid water.

The first rain hitting the earth's surface would have boiled away almost instantly. However, with the passage of time, water began to collect in the depressions in the earth's crust as global temperatures continued to cool.

Today, oceans cover about 70% of the surface with a volume of water of approximately 1.3 million km3. However, this huge amount of water only accounts for about 10% of the planet's total water with the rest of it chemically bound into the mineral deposits of the Earth's mantle.

By about 250 mya, it is estimated that there was just one landmass, the supercontinent of Pangea, which was surrounded by the single large ocean of Panthalassa. About 130 mya, at the end of the Jurassic Period, the continent of Pangea began to break apart into Laurasia in the north (comprised of present day North America, Europe, and Asia) and Gondwanaland to the south (which contained South America, Africa, India, Australia, and Antarctica).

The continental breakup and continual drift would lead to a shifting of global temperatures relative to the sun's position and the development of continental shelves off the coasts of the new landmasses. These more stable coastal waters would provide an environment more conducive to the evolution of the species.

The nature of the oceans today can be understood by analyzing certain chemical factors like pH, dissolved gases, salinity and nutrient content. Also central to the makeup of the oceans are temperature, sunlight and air movements in the constant interaction between the water and the atmosphere.


The salt content of seawater is approximately 35 0/00 (35 parts of salt per 1,000 parts seawater).


Salt                     g/kg                     %
Chloride                 19.0                    55.0
Sodium                   10.6                    30.6
Sulphate                  2.7                     7.7
Magnesium                 1.3                     3.7
Other                     1.0                     3.0

Environment Type                        Salinity (0/00)
Open ocean                              32-38
Coastal water                           27-30 (brackish)
Estuaries                                0-30
Enclosed sea (e.g. Baltic Sea)             25 or less
Hypersaline areas                          40 or more

Dissolved Gases

Many factors contribute to the amount of dissolved gases in seawater. Since oxygen (O2) and other gases are not readily soluble in saltwater, solubility will tend to decrease with rising water temperatures, increase with current turbulence and increase with salinity. Carbon dioxide (CO2) is another essential gas for biological processes in the ocean that create new organic matter. It is 60 times more concentrated in seawater than it is in the atmosphere. It forms carbonic acid (H2CO3), bicarbonate (HCO3) and carbonate (CO3).

Sea Temperature

Water temperature in the oceans is one of the most important factors controlling chemical, biological, and physical processes. Most importantly, it determines the biogeographic distribution of marine species throughout the oceans.

Suface temperature is influenced by the amount of solar radiation penetrating the water. Sunlight received by the ocean water will vary according to day length and cloud cover, as well as latitude and the time of the year, which will determine the angle of the sun and therefore its intensity. The heating effect of the sun is mostly confined to the surface; 98% of infared radiation is absorbed in the first meter of water. However, water has the unique property of absorbing large amounts of heat with little change to its temperature. The evaporation of surface water also helps to reduce surface temperature, allowing for ocean water to grow hotter and colder very gradually.

This slow process is vital to the support of life, as most organisms require time to acclimatise to the range of temperatures to which they are exposed. Poikilothermic (cold-blooded) animals cannot regulate their body temperatures and are therefore bound to smaller areas, which contrasts with homeothermic (warm-blooded) animals, which can adjust to fluctuating water temperatures and then travel across broad ranges of ocean water.

Biogeographical Zones:

Polar:           -1.9°C to +2.0°C (southern oceans)
Cold temperate:  -1.9°C to +5.0°C (Arctic waters)
                  5.0°C to 10.0°C (northern hemisphere)
                  2.0°C to 10.0°C (southern hemisphere)
Warm temperate:   10.0°C to 15.0°C (both hemispheres)
Subtropical:      15.0°C to 25.0°C (both hemispheres)
Tropical:         25.0°C and up (both hemispheres)

The World's Oceans:

Bibliography & Further Reading:

C.M. Lalli, T.R. Parsons. Biological Oceanography: An Introduction. 1993.
H.V. Thurman. Introductory Oceanography. 1994.

See Also:

Ocean Areas
Why is the ocean blue?
marine biology
Southern Ocean Islands
Pacific Ocean Islands
Atlantic Ocean Islands
Charles William Beebe
Marianas Trench
Ashmore Reef
Great Barrier Reef
oceans of the world
deep sea creatures
Jacques Cousteau



As a child I imagined that the ocean had nothing
on you in terms of vastness and the ability
to envelop and occupy space in such a way as to
comfort, scare, and, later, to frustrate.


You were four years a father to a little
brother (the man of the house at age ten).
You became an orphan when you lost your mother
at age fourteen. Just six years later
my arrival made you a real father.

Yours left one morning to assemble engines.
You've never talked about that day. The image
I've always had is a long grey school hallway,
your mother or uncle (or both) silhouetted
against the snowy sunlight streaming through
the double doors behind them.
You and Tom walk toward them, smiling, surprised,
with chilly red cheeks, still in your
secondhand coats, hats, mittens,
fresh from first recess.

I can never picture grandma doing anything
other than smiling. In every dream or mental
image I've ever had of her, she wears the same
self-conscious smile that she has on in the
only picture we ever had of her. Was she smiling
that day? What did she do to try to comfort you?
What did you do to comfort yourself? Her?

I sometimes wonder if the vivid, everyday
smell of bacon frying or the nondescript
sameness of every school hallway you have ever
walked bring that day back in an unstoppable
waterfall of blurry snapshot memories.
What was your father to you? Do you remember?
What is he now? How large or small is the
wake he left?


Your father’s brother took you in. A small
cabin-like home that now housed seven
became the place that we visited on
Christmases and Easters like some sort of
peculiar cemetery.

Something about the word “uncle” has
always left me with a feeling of rigid
detachment or loss and unable to make
up for the absence of a grandfather.
Nothing comforting or vast, tangible
but counterfeit in the ways that a roof
and open arms are never quite a home.


How must it have made you feel? Your uncle tried.
Did you feel he did? Or did he seem just
a poor substitute, a conch to hear the
ocean through, alone, while standing in a
bronze Michigan field.

O"cean (?), n. [F. oc'ean, L. oceanus, Gr. ocean, in Homer, the great river supposed to encompass the earth.]


The whole body of salt water which covers more than three fifths of the surface of the globe; -- called also the sea, or great sea.

Like the odor of brine from the ocean Comes the thought of other years. Longfellow.


One of the large bodies of water into which the great ocean is regarded as divided, as the Atlantic, Pacific, Indian, Arctic and Antarctic oceans.


An immense expanse; any vast space or quantity without apparent limits; as, the boundless ocean of eternity; an ocean of affairs.



© Webster 1913.

O"cean (?), a.

Of or pertaining to the main or great sea; as, the ocean waves; an ocean stream.



© Webster 1913.

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