The Sea at La Jolla, CaliforniaCredit:

How much salt is in saltwater anyway?  That is a good question, and the answer is surprisingly involved.  In fact, you could say it would take a whole article to thoroughly answer that question!  First, some basic terminology:  salt water or saltwater may refer to seawater, brine, brackish, or saline water.  The reason for this is salt levels in water can vary significantly, and there are different terms for a body of water based on its saltiness.  Salinity is the dissolved salt content of a body of water.  The dissolved content can include sodium chloride, calcium sulfates, magnesium, and bicarbonates. 

Let's assume that when someone asks how much salt is in saltwater, they are referring to seawater, that is, the open oceans.  We usually don't think about salt levels in water anywhere else besides the ocean.  This is probably due to the fact that you can taste the salt in the ocean even if you just accidentally get a little splash.  Anyone who has ever swum in the ocean knows this, and it's truly awful. 

Whereas the terms seawater and saltwater are a little more colloquial, salinity is a scientific spectrum with precise definitions.  From least salty to most salty, the spectrum defines salinity as:

Fresh water - any body of water with less than 0.05% salinity.

Brackish water - from 0.05 to 3% salinity.

Saline water - from 3 to 5% salinity.

Brine - any body of water with greater than 5% salinity. 

(Remember, percentages are based on the dissolved content of the water.)

As we all know, freshwater refers to lakes ponds, streams, lakes, rivers, aquifers, agricultural irrigation, and drinking water.  Humans cannot discern salt content in freshwater as it is too diluted or completely absent.  Brackish water is a term that not everyone may be familiar with.  It refers mainly to areas where freshwater and seawater mix, creating a transitional zone of salinity.  Some common geographical features which contain brackish water include estuaries, mangroves, and brackish lakes and seas such as the Black Sea and the Baltic Sea. 

Saline water is where the majority of the world's oceans fit into the spectrum.  The oceans range from 3.1 to 3.8% salinity, with an average of 3.5%.  Salt lakes also fall under the saline range.  So to answer the question posed in this article, salt water is about 3.5% "salty" which can also be described as 35 ppt (parts per thousand). 

Not to be forgotten is the last division, brine.  Brine is used to preserve meats, fish, fruits, and vegetables, but it also exists naturally.  Often times, brine can be found as groundwater, when it comes to the surface naturally it can be referred to as a "lick" or a "saline".  One of the most interesting places to find brine is in a place called a brine pool.  These are features of the deep oceans and are characterized by a pooling of higher salinity.  Brine pools do not mix well with the less saline water above it.  Submersibles have been known to bounce off of the top layer of a brine pool and cause visible ripples along the surface. 

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