How much salt is in the oceans?

If you’ve ever taken a mouth full of seawater, you already know that the oceans are very salty. About 70% of our planet is covered by water, and most of that water is contained in the world’s oceans. That’s a lot of salty water! But have you ever wondered how much salt is in the oceans? And how did that salt get there in the first place?

When the earth was still forming, the land was covered by erupting volcanoes that spewed gases into the air. Those gases dissolved into the early oceans, which is how they became salty in the first place. They remain salty today because all rain that falls and all water that flows over the surface of the planet ends up in the ocean. As it flows across rocks and through soil, more salt dissolves in the water and is carried to the ocean.

So how much salt is that? The saltiest ocean is the Atlantic, and the least salty are the oceans at the poles, but all of them have a lot of salt. That means if we managed to dry up all the water in the oceans, the seabeds would be covered by a pile of salt as tall as a 12 storey building!

If we managed to get all that salt together, we could use it to build a wall a mile wide and 180 miles tall. That wall would stretch all the way around the world at the equator.

That’s a lot of salt!