How Much of the world is covered by oceans?

Those privileged few who have seen the Earth from orbit frequently describe it as a beautiful blue marble. This is a result of the planet’s surface being mostly covered in water. Water does not naturally reflect blue light, although it can appear blue when it does.

The majority of our earth is covered in water, which is a well-known truth for those of us who have limited ability to live on the surface. But how much water exactly makes up our planet? The answer is a little more involved than you may imagine and takes into account many distinct criteria like most facts about our world do. You may visit How to Visualize the Size of the Planet Earth if you want to explore more ideas.

planet earth

In simple terms, around 71% of the Earth’s surface is made up of water, with continents and islands making up the remaining 29%.

96.5% of the water on Earth is found as salt water in the seas, with the remaining 3.5% being freshwater lakes and frozen water that is trapped in glaciers and polar ice caps. Almost all of the freshwater—69% of it, to be exact—turns into ice. The sea levels would rise to a height of 2.7 km if you could melt all that ice and the Earth’s surface was smooth.

A remarkable amount of water also exists underneath the surface of the Earth, in addition to the water that is seen as ice. The volume of all fresh water on Earth, if it were to be condensed into a single mass (as in the image above), is thought to be around 1,386 million cubic kilometers (km3).

The total volume of water that is present as surface water, groundwater, rivers, lakes, and streams is just over 10.6 million km3, or slightly more than 0.7%. The finite and priceless nature of freshwater is made abundantly obvious when seen in this light.

But how much of Earth is made up of water, and how much of that water makes up the planet’s real mass? This refers to both the inside and the outside of the Earth.  the Earth’s oceans have a combined mass of 1.35 x 1018 masses, or 1/4400 the planet’s overall mass. In other words, although covering 71% of Earth’s surface, the seas only make up 0.02% of the planet’s overall mass.

How much of earth is water

Two long-standing mysteries about our planet are the formation of water on its surface and why it has more water than any other rocky planet in the Solar System.

Our planet was thought to have originated dry some 4.6 billion years ago, with a molten surface being created on the young Earth by high-energy collisions. This hypothesis states that ice comets, trans-Neptunian objects, or water-rich meteoroids (protoplanets) from the outer regions of the main asteroid belt impacting the Earth supplied water to the world’s seas.

meteorite-falling-from-night-sky

Examining meteorites assumed to have originated at various points in the Solar System’s history led researchers to this conclusion. The oldest meteorites, carbonaceous chondrite, which date back to the very early Solar System, were discovered to share the same chemical composition as meteorites coming from protoplanets like Vesta. There is significant water present in this.

Approximately 11 million years after the Solar System’s creation, these meteorites are dated to the same period during which water is thought to have originated on Earth. In other words, it seems that water was being deposited on Earth by meteorites in its early days.

These results show that there was enough water already present for life to have started earlier than imagined, while they do not completely rule out the idea that some of the water that currently covers 71 percent of Earth may have come later.

These results show that there was enough water already present for life to have started earlier than imagined, while they do not completely rule out the idea that some of the water that currently covers 71 percent of Earth may have come later.

The world’s oceans are on average roughly 3800 meters (12,500 feet) deep, which is about four times more than the height of the typical land surface (840 meters or 2800 feet). In actuality, Mt. Everest, the highest point on land, is 8848m (29,028ft) tall, while the Marianas Trench’s Challenger Deep, the deepest region of the ocean, is around 10,920m (36,200ft) deep. Mt. Everest would therefore still be covered by more than 2 kilometers of water even if submerged in the Marianas Trench. Earth has more water than land, thus even if the land elevation were to be flattened, there would still be 2700 meters of water covering the entire planet.