Why is the Ocean Salty?


. . and why did it take us so long to find out? Nat Geo Explorer Robert Ballard explains. (Nat Geo News)

Build your own ocean with our fun matching game!

Teachers, scroll down for a quick list of key resources in our Teachers’ Toolkit—and a round-up of other interesting reads this week.

Note: Current Event Connections is slowing down for the summer. Our column will continue to appear once or twice a week until mid-August. If you have an idea for a Current Event Connection, a recommendation for a good read, or want to share one of your MapMaker Interactive maps, let us know in the comments!

Discussion Ideas

  • Watch the super-short, delightful “Campfire Story” with Nat Geo Explorer-in-Residence Robert Ballard. So, how did the ocean get so salty?
    • The ocean’s chemistry (including its salinity) is due to the weird and wonderful workings of hydrothermal vents.
      • Hydrothermal vents eject chemicals from deep beneath the Earth’s surface to the surrounding seawater. In particular, Ballard points to beautiful “black smokers,” a type of hydrothermal vent that ejects what looks like billows of black smoke—in fact, he explains, the dark “smoke” is actually “microcrystals of minerals.” (Salt is a mineral!)


  • Before the discovery of black smokers in 1979, how did oceanographers like Robert Ballard think the ocean’s chemistry developed?
    • Rivers. Oceanographers thought that “rivers were the obvious culprit, bringing all this stuff in” as they emptied into the sea. (“Stuff” being chemically rich sediments eroded from continental landforms.)




Nat Geo: Why is the Ocean Salty? video

Nat Geo: My Ocean game

Nat Geo: Ocean Explorer: Robert Ballard article

Nat Geo: Deep Sea Hydrothermal Vents video





3 thoughts on “Why is the Ocean Salty?

Leave a Reply