Seawater, or salt water, is water from a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5%. This means that every kilogram of seawater has approximately 35 grams of dissolved salts. The average density at the surface is 1.025 kg/L. Seawater is denser than both fresh water and pure water because the dissolved salts increase the mass by a larger proportion than the volume. The freezing point of seawater decreases as salt concentration increases. At typical salinity, it freezes at about −2 °C. The coldest seawater still in the liquid state ever recorded was found in 2010, in a stream under an Antarctic glacier: the measured temperature was −2.6 °C. Seawater pH is typically limited to a range between 7.5 and 8.4. However, there is no universally accepted reference pH-scale for seawater and the difference between measurements based on different reference scales may be up to 0.14 units.

Read more in the app

New Prototype Device Generates Hydrogen From Untreated Seawater

Seawater split to produce 'green' hydrogen

A New Chapter in Climate Science – 390-Million-Year-Old Seawater Pockets Uncovered

A New Simple Process Extracts Valuable Compounds From Seawater

Electrolysis of seawater to make hydrogen

Synthetic fibers discovered in Antarctic air, seawater, sediment and sea ice as the 'pristine' continent becomes a sink for plastic pollution

Tiniest ever ancient seawater pockets revealed: The surprising discovery of seawater sealed in what is now North America for 390 million years opens up a new avenue for understanding how oceans change and adapt with the changing climate

Tiniest ever ancient seawater pockets revealed

Egg whites could be key to removing microplastics from seawater. An egg-based aerogel cleans water without hurting the environment.

Clean hydrogen fuel is easier to produce from seawater with stable hierarchical electrocatalysts

Simple process extracts valuable magnesium salt from seawater

“Wind-Ruffled Waves, Foam and Wave Shadows, Above Natural Blue Seawater.” This is how we’ll Spot Exoplanets With Oceans

Early Earth: Tungsten isotopes in seawater provide insights into the co-evolution of Earth's mantle and continents

Scientists Just Found a Vast Aquifer of Ancient Seawater Below Antarctica

'Giant MRI of Antarctica' reveals 'fossil seawater' under ice sheet

'Giant MRI of Antarctica' reveals 'fossil seawater' under ice sheet

From Seawater to Drinking Water at the Push of a Button – With No Filters!

From seawater to drinking water, with the push of a button: Researchers build a portable desalination unit that generates clear, clean drinking water without the need for filters or high-pressure pumps

From seawater to drinking water, with the push of a button

Surfer science supports seawater study