The oceanic crust is much thinner, ranging from 5 to 10 km thick. The continental crust has an average density of 3.0 g/cm3 and is composed primarily of felsic rock.

Cuba is located in the northern Caribbean where the Caribbean Sea, Gulf of Mexico and Atlantic Ocean meet. It is east of the Yucatán Peninsula (Mexico), south of both the U.S. state of Florida and the Bahamas, west of Haiti and north of both Jamaica and the Cayman Islands.

In marine geology, a guyot , also known as a tablemount, is an isolated underwater volcanic mountain (seamount) with a flat top more than 200 m (660 ft) below the surface of the sea. The diameters of these flat summits can exceed 10 km (6.2 mi).

The ocean basins are huge depressions of great depth, usually more than 2000 m, having basaltic floors with varying topographic feature. Nearly 70.8 per cent of the earth's surface is covered by water. The ocean has saline water body and home of nearly 1.4 lakh species and also believed the first homes of all living organisms.

The smallest sea on Earth is the Baltic Sea. This sea is about 146,000 square feet. It lies along the Scandinavian Peninsula in Northern Europe and is bordered by Poland, Russia, Sweden and Finland.

Bandar-e Būshehr, also called Būshehr, Bushir, Bushire, or Būshahr, port city and capital of Būshehr province, southwestern Iran. It lies near the head of the Persian Gulf at the northern end of a flat and narrow peninsula that is connected with the mainland by tidal marshes.

The Sea of Okhotsk covers an area of 1,583,000 square kilometres (611,000 sq mi), with a mean depth of 859 metres (2,818 ft) and a maximum depth of 3,372 metres (11,063 ft).

Over millions of years of rain, rivers and streams have washed over rocks containing the compound Sodium Chloride and carried it into the seas and oceans.

Salinity is the saltiness or dissolved salt content in a body of water. Salinity is an important factor in determining many aspects of the chemistry of natural waters and of biological processes within it, and is a thermodynamic state variable that, along with temperature and pressure, governs physical characteristics like the density and heat capacity of the water.

The Oceanic relief features are in the form of mountains, basins, plateaus, ridges, canyons and trenches beneath the ocean water. These forms are called Submarine Relief.

Factors affecting salinity in surface layers of ocean include:

1. The salinity of water in the surface layer of oceans depends mainly on evaporation and precipitation.
2. Surface salinity is greatly influenced in coastal regions by the fresh water flow from rivers, and in polar regions by the processes of freezing and thawing of ice.
3. Wind, also influences salinity of an area by transferring water to other areas.
4. The ocean currents contribute to the salinity variations.
5. Salinity, temperature and density of water are interrelated. Hence, any change in the temperature or density influences the salinity of an area.

The surface of the planet is approximately 71% water and contains (5) five oceans, including the Arctic, Atlantic, Indian, Pacific and Southern. Their borders are indicated on the world image (above) in varied shades of blue. These were divided by the Geographers who were exploring the world.

Although many factors combine to influence weather, the four main ones are solar radiation, the amount of which changes with Earth's tilt, orbital distance from the sun and latitude, temperature, air pressure and the abundance of water.

Panthalassa was the superocean that surrounded the supercontinent Pangaea. A superocean is an ocean that surrounds a supercontinent. It is less commonly defined as any ocean larger than the current Pacific Ocean. The movement of Earth's tectonic plates formed Pangaea and ultimately broke it apart. Pangaea existed during the Permian and Triassic geological time periods, which were times of great change.

After 2000m, the temperature of the seawater is uniform everywhere. It is around $4^0C$ according to depth. And therefore, the water of greater depths does not freeze.

Precipitation is the main source of potable water available of the earth. Snow, hailstones, rainfall, are the major forms of precipitation.

Oceans provided abundant food resources like fish and salt.

Temperate is one of the major property of seawater. It always varies from region to region. The surface temperature of the sea water decreases from the equatorial area towards the poles. Some factors which effects the temperature of sea water are:-

• Cyclone
• Rainfall
• Salinity
• ocean currents
• pollution

As the salinity of the landlocked seas is more, the temperature of these landlocked seas is higher than the open seas. Aral sea is landlocked sea.

Crude oil and natural gas occur in 'pockets' under the ground. Sometimes the deposits are found under the sea bed. Like other deposits, they are extracted by drilling a hole down through the rocks into the oil or gas. For undersea deposits, the drills are mounted on a platform called a drilling rig.

The movement of ocean waters or ocean currents takes place due to the effect of earth's rotation, wind difference, salinity and density of seawater, etc. The current in the ocean is originated due to the combined effect of all these factors acting internally as well as externally. 

After 2000m, the temperature of the seawater is uniform everywhere. It is around $4 ^oC$ according to depth. And therefore, the water of greater depths does not freeze.

Temperate is one of the major property of seawater. It always varies from region to region. The surface temperature of the sea water decreases from the equatorial area towards the poles.

In mid-latitudinal zones, rainfall is less and the supply of freshwater from various rivers is also low. This zone has the hot deserts of the world. 

In seas where the supply of freshwater exceeds the rate of evaporation, salinity is low. Near the estuaries generally the salinity is low because ample amount of fresh water enters the sea or ocean.

Because of the sun's heat, evaporation happens at a faster rate. Evaporated water turns into water vapour and reduces in quantity. But amount of salt remains the same in the remaining water and therefore the salinity of the water increases.

The uneven distribution of temperature on earth, uneven supply of freshwater, etc. affects the salinity of seawater. If temperature is high, evaporation will be high and it will result in high salinity. Again if evaporation is high but supply of fresh water exceeds evaporation than salinity will be low. So in many ways the salinity of sea water is effected.

Salinity is the amount of salt dissolved in a body of water. Salinity is an important factor in determining many aspects of the natural waters and of biological process within it, and is a thermodynamic state variable that, along with temperature and pressure, governs physical characteristics like the density and heat capacity of the water.

Temperature and salinity are the two properties of sea water that control the density of the sea water. If temperature reduces, density of water increases.

In tropical zone, temperature is generally higher than the other parts and so the rate of evaporation is also higher, therefore, salinity is higher.

In seas where the rate of evaporation is high than the supply of freshwater, salinity is high. It happens because due to evaporation water turns into water vapour and reduces in quantity, but the amount of salt remains the same.

In the polar areas, temperature is very low and hence evaporation is also very less in polar areas, so salinity is low.

Salinity is not affected much in seas where both the supply of freshwater and evaporation of water is low. Because in both the reasons salinity almost remains the same.

False,

The heavier silicates named 'Sima' or silica + magnesium are most aboundant in the ocean floor.

Ocean water is constantly in motion: north-south, east-west, alongshore, and vertically. Seawater motions are the result of waves, tides, and currents. Ocean movements are the consequence of many separate factors: wind, tides, Coriolis effect, water density differences, and the shape of the ocean basins.

The oceans absorb heat near the equator and then transport that solar energy to polar regions. The oceans also moderate the climate within a region. Along with coastal areas, summer temperatures are not as hot, and winter temperatures are not as cold, because water takes a long time to heat up or cool down.

The Panama Canal is a waterway that connects the Atlantic and the Pacific Ocean. Before the canal was opened in 1914 ships had to travel around the southern tip of South America to get from the Atlantic to the Pacific Ocean. The Panama Canal shortens the journey by about 11000 km.

Ocean thermal energy conversion (OTEC) uses the ocean thermal gradient between cooler deep and warmer shallow or surface seawaters to run a heat engine and produce useful work, usually in the form of electricity