Oceans cover about 70% of the Earth's surface and contain about 95% of all the life-giving water supply. Our oceans are unique in that there are no other planets in our solar system containing liquid water. All life originated in the seas, and the oceans of today continue to provide a home for an incredibly diverse web of life. The oceans also directly influence the weather and climates, and when earthquakes occur offshore, tsunamis are sure to make a profound statement with their powerful energy and destruction.
The Earth's oceans are all connected to one another. There are seven oceans which cover our planet Earth. They include the Pacific Ocean, Atlantic Ocean, Indian Ocean, Southern Ocean and Arctic Ocean. Even though many people, including scientists, have been fascinated by the world's oceans, we have only explored less than five percent of it. Fortunately, there are some scientists who are working practically non-stop to explore the other 95 percent. The five basic physical properties that determine the Earth's major oceans are light, temperature, depth, pressure, and salinity.
The Pacific Ocean is located between the Americas to the East of the Pacific Ocean Basin and the Asian and Australian continents. It is the largest and deepest of all oceans and is home to a string of volcanoes and sites of seismic activity known as the "Ring of Fire". The Pacific ocean also contains the deepest sea trench in the world known as the Marianas trench, which measures to a depth of 35,827 feet. Along the equator, surface temperatures can reach 86 degrees Fahrenheit, while near the poles, temperatures are at freezing point or colder. The floor of the ocean is largely a deep-sea plain with many swells, such as volcanoes, seamounts, and guyots.
The Atlantic Ocean lies between the continents of America, Europe, and Africa. The Atlantic Ocean is the world's second to the largest; however, it is still growing as two of its tectonic plates (Eurasian and North America) are continually spreading apart (divergent boundary) at an average rate of 2.5 cm per year. The center of this region for seafloor spreading is called the Mid-Atlantic Ridge. It is mostly underwater, but some portions of it have enough elevation to extend above sea level. The ridge spreads from Ireland to Antarctica beneath the Atlantic Ocean.
Located between Africa, Australia and Asia, the Indian Ocean is the third to the largest of the world's oceans. It is also known for having the warmest surface temperatures of the world and providing an ideal marine environment for the humpback whales. Once thought to be extinct, a fish known as Coelocanth, also lives in the Indian Ocean near the Comoro Islands between Mozambique and Madagascar. The Indian Ocean provides major sea routes connecting the Middle East, Africa, and East Asia with Europe and the Americas. About 40 percent of the world's oil production comes from the Indian Ocean.
The Southern Ocean is located around the South Pole across the Antarctic Circle in the southern hemisphere. It is regarded as the fourth-largest ocean of the world. Fluctuating seasonally, this ocean zone is where cold, northward-flowing waters from the Antarctic mixes with the warmer sub-antarctic waters. Typical depths of the ocean are anywhere from 13,000 to 16,000 feet. Icebergs can occur at anytime of the year throughout the Southern Ocean, so ships must stay clear to avoid collision. Penguins and albatrosses live in the Antarctic region without fear of predators such as polar bears.
The Arctic Ocean is located around the North Pole across the Arctic Circle. Of the five, it is the smallest and shallowest of the world's oceans and provides a safe haven for the polar bears. The Arctic region is the only place on Earth where polar bears naturally live. Due to global warming (by mostly natural causes), the Arctic ice sheets are presently melting at 8 percent every ten years. Although shrinking, the Arctic ice sheets are amazingly four times larger than the state of Texas. Temperatures of the icy waters vary from - 86 to -158 degrees Fahrenheit year round. During the long winter months, the Sun never rises above the horizon for a period of four months.
Alvin is a manned deep-diving submersible measuring 24.93 feet long and weighing 17 tons. Owned by the United States Navy and operated by the Woods Hole Oceanographic Institution, it has made over 4,400 dives carrying two scientists and a pilot. It can cruise at a speed of 1 knot and reach depths as great as 13,000 feet. Alvin has allowed scientists to observe many life forms that are able to cope with super-pressures and move about in total darkness. Scientists also use the submersible for exploration of the wrecked Titanic. Alvin operates two robotic arms and is fitted with mission-specific sampling and experimental gear. Normal dives with the submersible can last 6 to 10-hour.
An atoll is a ring of coral reefs or low-lying coral islands encircling a lagoon. Large numbers of atolls exist in the Pacific and Indian oceans. While visiting several atolls in 1842, Charles Darwin explained the way in which they form from a volcanic island. As a volcanic island ages, it gradually sinks due to the compression of the seafloor that it sits on. If the sinking island has a thriving community of coral organisms living nearby, a fringing reef will form around them. As the island sinks further, this turns it into a barrier reef, thus separating the sinking island as a lagoon. Finally, the island sinks altogether and leaves behind an atoll.
The Bermuda Triangle is a region in the western part of the North Atlantic Ocean in which ships, planes, and people mysteriously disappear. Some scientists speculate that unknown forces, such as oceanic flatulence (methane gas erupting from ocean sediments) and disruptions in geomagnetic lines of flux account for many of the unexplained disappearances. Many scientists believe that the disappearances are related to environmental forces because the majority of the Atlantic tropical storms and hurricanes pass through the Bermuda Triangle. Also, the Gulf Stream can cause rapid, sometimes violent changes in weather.
When a summit of a submarine volcano reaches the surface, it sometimes erupts enough material to form an island. Most island volcanoes erupt ash and cinder and/or molten lava. Ephemeral islands are usually short-lived as they are eroded away by wave action. The term ephemeral refers to lasting one day, transitory, or existing only briefly. For a long-lived island to form, a series of vigorous eruptions, especially molten lava, must occur over many years. This ensures that the lava will bind the loose rock, ash, and cinders into a tough, wave-resistance rock material. And of course, the deeper the water and less wave action there is, the better chances it has for survival.
The giant squid is a deep-ocean dwelling squid in the family of Architeuthidae, which has eight different species. They can measure anywhere from 15 to 25 feet in length; however, the largest giant squid ever recorded by scientists measured 43 feet and may have weighed nearly a ton. In 2012, a group of scientists from Japan's National Science Museum along with colleagues and the Discovery Channel crew filmed a giant squid in its natural habitat. Like other squids and octopuses, they have two eyes, a sharp beak, eight arms, two feeding tentacles, and a funnel called a siphon.
Great White Sharks:
The Great White Shark (Carcharodon carcharias) is the largest known predatory fish and apex predator for the coastal surface waters of all major oceans. Adults can reach up to 21 feet in length, although some have been known to measure 26 feet in length and weight 7,328 pounds. Such adult sharks can live up to 15 years of age, but some have been found up to 30. The Great White is known for its conical snout, torpedo-shaped body, pitch-black eyes, and triangular shaped teeth with sharp serrations. Of all shark attacks, the Great White is responsible for the largest number of fatal unprovoked attacks.
A guyot is a flat-topped sea mount with its top usually more than 660 feet below sea level. Most are observed within the Pacific Ocean. When a volcanic island becomes inactive and sinks, coral reef formations may halt at some point. Some may have never even started if the island exists in a region where coral-reef-forming organisms do not thrive. In this case, a guyot may form. As the island sinks, its top is worn down flat by wave action, wind, and atmospheric processes. The flat top is retained as the island continues to sink. Some guyots are over 100 million years old, and the largest of them rise as high as 2.5 miles above the seafloor.
Hydrothermal vents occur at numerous spots in the oceans. At such places, geysers expel plumes of extremely hot, mineral-rich water that gushes out of fissures and chimney-shaped tubes protruding up from the seafloor. These geysers are commonly called black or white "smokers" on account of the dark or light minerals that precipitate out of them. Hydrothermal vents are created when seawater seeps down through the cracks of the seafloor and become heated by hot rocks surrounded by magma. As with all heat, the hot water rises upward to the cooler seafloor, and as it cools, minerals precipitate to form solid particles. The heat and dissolved minerals surrounding the vents provide a safe haven for some extraordinary marine communities, such as shrimp, crabs, mussels, and tube worms. Such areas are too deep for light to penetrate through, so the communities rely on specialized microbes to obtain their energy.
The Marianas Trench is the deepest part of the world's oceans and is located in the western Pacific Ocean just east of the Mariana Islands. The trench is about 1,580 miles long and has an average width of 43 miles. It reaches a maximum known depth of 6.831 miles; however, the deepest portion of the trench, known as the Challenger Deep, measures at a depth around 6.85 miles. The deep trench was formed as a result of convergence as the Pacific Plate subducted beneath the Mariana Plate that lies to the west.
Large waves caused by storms at sea are always a hazard to shipping, however, roque waves are something quite different. Such waves are rare and unusually large that measure more than twice the average height of larger storm waves observed in the sea area and ocean. They can reach up to 100 feet high and their existence has only been confirmed by satellite imaging since 1995. Their exact cause is not known, but they probably form from a combination of strong winds and fast currents having a focusing effect that joins a number of normal-size waves together. Roque waves are considered particularly dangerous.
Seamounts are mountains that rise at least 3,280 feet from the sea floor. Most are the remains of submarine volcanoes that did not quite grow large enough to form volcanic islands. After the volcanoes become extinct, they gradually subside and erode away to seamounts. Isolated in the deep ocean, they often provide habitats for a variety of marine life which are adapted to shallow waters. Underwater currents are forced upward near the seamounts and bring nutrient-rich water closer to the surface. Such waters support plankton, which in turn, provide food for many types of marine life.
Sea Vortexes (Whirlpools):
When ocean currents converge, meet underwater obstructions, or interact with strong winds, whirlpools can form. A whirlpool is a swirling body of water produced by the meeting of opposing currents. The majority of whirlpools are not very powerful; however, some have been known to completely destroy boats and take lives. Whirlpools in oceans are usually caused by tides. For example, the Corryvreckan Whirlpool located on the west coast of Scotland is caused by seawater rushing through a narrow strait between two islands twice a day and interacting with the seabed features. It is regarded as violent and dangerous.
About 80 percent of the world's volcanic activity occurs in the oceans. New volcanoes are continually being formed near mid-ocean ridges, over hop spots, and within volcanic island arcs. These volcanoes grow upward with a few of them eventually reaching the surface to produce some highly dramatic eruptions. Lo'ihi, a submarine volcano just southeast of the Big Island of Hawaii, is now presently reaching a height of 3,179 feet. Extensively studied by submersibles, the underwater volcano has been growing for about 400,000 years over the hot spot that formed all of the Hawaiian Islands. It's just a matter of time when the Lo'ihi volcano will make its grand appearance.
A tsunami is a powerful pulse of energy that can propagate for a great distance on the ocean surface in the form of high-speed waves. Hardly noticeable in the open ocean, tsunami waves dramatically increase in size when they reach shallow waters. Such waves can cause a huge amount of destruction as they surge onshore. The initial signs of a tsunami about to hit shore vary, depending on whether a wave trough or crest arrives first. If a trough come first, the sea recedes dramatically, whereas in the case of a crest, a large incoming wave appears. As it reaches shallow water, the wave slows to less than 50 mph, but its height increases drastically, in extreme cases up to several 100 feet.
Tornadoes over water are called "water spouts". They are weak vortices that consist of a column of cloud droplets that can be amplified above the ocean's surface, spraying large volumes of seawater. Interestingly, water spouts do not suck up water from the oceans or seas. The water seen from the funnel cloud is actually water droplets formed by condensation. They commonly occur in tropical and subtropical seas where there is a on-going supply of warm, moist air. Water spouts can be dangerous posing threats to water craft, air craft, and swimmers. Water spouts commonly occur over the sea but occasionally make it to the land. Photo: Twin water spouts whirling near Discovery Bay, Jamaica.