1. How many oceans?

There is one global ocean, it is divided into five regions: the Pacific, Atlantic, Indian, Arctic, and Southern. The ocean regions are also divided into smaller zones based on their depth and distance from the shore. These zones are intertidal, pelagic, abyssal, and benthic. The intertidal zone is where the ocean meets the land and is affected by tides. The pelagic zone is the open water where most fish and marine mammals live. The abyssal zone is the deep sea where light does not reach and pressure is very high. The benthic zone is the bottom of the ocean where sediments and organisms accumulate.

2. Which ocean (region) is the largest?

The Pacific is the largest and deepest.

Ocean region	Area square miles	Volume Cubic miles	Ave Depth Feet	Coastline miles
Pacific	65,144,000	170,000,000	13,024	84,297
Atlantic	32,879,000	85,100,000	11,962	69,510
Indian	27,243,000	63,000,000	12,274	41,337
Southern	8,478,800	17,226,000	10,728	11,165
Arctic	6,007,000	5,430,000	3,953	28,203
total	139,751,800	333,000,000		234,512

(1 cubic mile contains 1.1 trillion gallons)

3. How deep is the deepest point?

The deepest known area of the Earth’s oceans is known as the Mariana Trench in the Pacific Ocean. Its deepest point measures 36,000 feet (over 6.8 miles).

4. The ocean has many different levels and features, such as mountains, trenches, currents, waves, and ecosystems. The longest mountain range in the world is the Mid-Oceanic Ridge, which stretches over 34,800 miles along the ocean floor

5. The sea is home to the world’s largest living structure – the Great Barrier Reef. Measuring around 1,615 miles.

6. How much water is in the ocean?

The ocean contains 352 quintillion (352,000,000,000,000,000,000) gallons of water! Water enters the ocean from rivers and melting ice and leaves the ocean into the atmosphere through evaporation.

7. How many animals are believed to live in the ocean?

Because so much of our oceans remain unexplored, it is impossible to know just how many species of animals call its waters home. Scientists estimate that 91 percent of ocean species have yet to be classified, which makes Nautilus’ work vital. One study found that there are at least 228,450 known species in the ocean — and an estimated 2 million that have yet to be discovered.

8. How many shipwrecks are in the ocean?

The seafloor provides an often-untouched record of human history, making it an important target of exploration for archeologists studying the complex chronicles of humanity. It is estimated that 3 million shipwrecks can be found across the ocean floor around the planet — most of which have yet to be discovered!

9. What is the average depth of the ocean?

The average depth of the ocean measures about 12,100 feet — or about 2.3 miles down! The age and size of an ocean influences its depth. The Pacific is the deepest basin of the global ocean.

10. How big is the ocean?

The majority of our planet’s surface is covered in water! The world’s ocean covers 71% of Earth’s surface, which equates to around 139 million square miles of salty blue.

11. What percentage of the seafloor remains to be mapped?

We have better maps of Mars than we do our own ocean! As of June 2020, The Nippon Foundation-GEBCO Seabed 2030 Project, which aims to facilitate the complete mapping of the global ocean floor by 2030, just one-fifth of the world’s entire ocean floor has been mapped. That equates to maps of only an area twice the size of Australia!

12. What is the pressure at the bottom of the ocean?

For every 33 feet of depth, the pressure of the ocean increases by one atmosphere. At the bottom of the Mariana Trench — the deepest part of the ocean — the pressure is more than 16,000 pounds per square inch (PSI). By comparison, the sea level surface air pressure humans exist in daily is 14.7 PSI.

13. How many volcanoes are under the ocean?

Most of our planet’s most active volcanic systems are underwater below 6,500 feet. Altogether, there are an estimated 75,000 volcanoes rising more than a half-mile above the ocean floor.

14. How much oxygen does the ocean produce?

Tiny photosynthetic organisms, known as phytoplankton, help to turn sunlight into oxygen, just like plants do on land. Scientists believe that about 70% of oxygen produced on Earth comes from our oceans.

15. How deep can light penetrate the ocean?

When exploring the deep waters of our oceans, ROV Hercules brings its own lighting system. That’s because sunlight entering the water can only travel up to 3,200 feet under the best of conditions, but in most cases is unable to penetrate beyond 650 feet.

16. The Atlantic and Pacific oceans meet at the southernmost tip of South America. So why the necessity of locks at the Panama Canal?

In fact, water levels on the opposite sides of Panama average less than a foot different, mostly due to currents, tidal variations, etc. The canal needs locks in order to raise ships high enough to cross the Continental Divide. The ships traverse man-made Gatun Lake about 80 feet above sea level and are then lowered to head downward on the other side.

In other words, even if sea levels were exactly the same on the Atlantic and Pacific sides, the Panama Canal would still need locks.

17. Why does the ocean have tides.

Tides are the periodic rise and fall of the sea level caused by the gravitational pull of the moon and the sun on the earth. The moon has a stronger influence on the tides than the sun because it is much closer to the earth. The tides vary depending on the position of the moon and the sun relative to the earth.

When the moon and the sun are aligned, they create higher high tides and lower low tides, called spring tides. When the moon and the sun are at right angles to each other, they create lower high tides and higher low tides, called neap tides. The tides also depend on the shape of the coastline, the depth of the water, and the local weather conditions.

Tides are important for many reasons, such as providing habitats for marine life, influencing ocean currents, and affecting human activities like fishing and navigation.

18. What is the difference between a sea and the ocean?

These two terms are often used interchangeably, but they have different meanings in geography.

A sea is a smaller part of an ocean that is usually surrounded by land or islands. For example, the Mediterranean Sea is a part of the Atlantic Ocean that is bordered by Europe, Africa, and Asia. The Caribbean Sea is another part of the Atlantic Ocean that is enclosed by Central America and the Caribbean islands. Some seas are not connected to any ocean, such as the Caspian Sea or the Dead Sea, which are actually large salty lakes.

The main difference between an ocean and a sea is that an ocean is bigger, much deeper and more open than a sea. A sea is a large body of saltwater (no official minimum size) more influenced by the land around it, which affects its climate, salinity, biodiversity, and human activities.

There are only five oceans (regions) and 28 seas in the world. Most seas are found on the coastline and are actually a part of the ocean.

19. How much salt is there in ocean water?

On average, seawater in the world's oceans has a salinity of about 3.5%. This means that every gallon of seawater has approximately 4.8 oz of dissolved salts. Predominantly sodium (Na+) and chloride (Cl−) ions. Seawater is denser and therefore more buoyant than fresh water because the dissolved salts increase the mass by a larger proportion than the volume.

It uses less energy for a swimmer keeping afloat and more used to propel.

The freezing point of seawater is about 28 °F.