Ocean Salinity: How Much Salt is in Oceans?

How Much Salt is in Oceans?

Imagine you’re stranded on a raft in the middle of the ocean. All this water. But nothing fresh to drink.

Oceans are salty because runoff transports minerals and salts from the surface. When the ocean evaporates from heat, salt remains in the ocean and water rises.

Even though rainwater washes minerals and salts into rivers and lakes, they are mostly freshwater. This is because their minerals get washed away and transported to an outlet at the nearest ocean.

So unlike salty oceans, lakes, and rivers constantly have the minerals washed away.

How much total volume is salt water?

Imagine you’re stranded on a raft in the middle of the ocean. You see nothing but open water. But none of it is freshwater to drink. If you compare saltwater and freshwater:

SALTWATER: about 97.2% is not suitable for drinking because it has salt in it.
FRESH WATER: If we sum up all the sources of freshwater, about 2.8% of water on Earth is freshwater.

The majority of saltwater is from the 5 oceans that surround continents. And the average depth of oceans is 2.7 kilometers so water volume is about 1,338,000,000 cubic kilometers.

Oceans are the foundation of the water cycle. Water moves continuously in nature in three stages: evaporation, condensation, and surface runoff.

Ocean currents are like giant conveyor belts moving huge amounts of water all the time. While wind drives surface ocean currents from the Coriolis effect, temperature and salt gradients mostly influence deep ocean currents.

What is the distribution of fresh and saltwater?

Earth is unique because of how much water it stores. But the distribution of the total volume of water differs disproportionately for fresh and salt water.

If you crunch the numbers, Earth holds about 326 million trillion gallons (326,000,000,000,000,000,000 gallons) of water. As already mentioned, most of the water is saltwater. Just a small portion of it is freshwater.

Here’s the percentage and total (in gallons) for the global water distribution of all sources of water.

Source	Gallons	Percentage
Oceans	316,872,000,000,000,000,000	97.2%
Glaciers	6,846,000,000,000,000,000	2.1%
Groundwater	2,119,000,000,000,000,000	0.65%
Lakes	55,420,000,000,000,000	0.017%
Soil Moisture	16,300,000,000,000,000	0.005%
Streams, wetlands and swamps	3,260,000,000,000,000	0.001%
Total	326,000,000,000,000,000,000	100%