
About this episode
And no, we're not talking about an underground sea with waves, fish, and a shoreline.
Something much stranger is happening deep beneath our feet.
Far below Earth's surface, scientists have discovered evidence that enormous amounts of water may be locked inside a mineral called ringwoodite.
Ringwoodite exists deep within Earth's mantle, roughly 410 to 660 kilometers beneath the surface.
And here's the strange part:
The water isn't necessarily sitting there as a liquid ocean.
It's locked into the crystal structure of the rock itself.
Think of it less like a giant underground swimming pool...
and more like an enormous sponge made of minerals, storing water inside its atomic structure.
Scientists became particularly interested in this because laboratory experiments showed that ringwoodite can contain significant amounts of water.
Then, in 2014, researchers announced the discovery of a tiny piece of natural ringwoodite trapped inside a diamond from deep within Earth.
That was important because it provided direct evidence that this water-rich mineral actually exists naturally deep inside the planet.
Some scientists have estimated that the transition zone between the upper and lower mantle could potentially contain an amount of water comparable to, or even greater than, the amount in Earth's surface oceans.
But there's an important catch.
We don't know that the entire region is completely saturated with water.
And the water isn't necessarily free liquid water.
It's chemically bound within minerals.
So why does this matter?
Because this hidden water could be part of Earth's enormous deep water cycle.
Water from the surface can eventually be carried downward through subduction, where tectonic plates sink into the mantle.
Under extreme pressure and temperature, that water can become incorporated into minerals.
Later, geological processes can move water back toward the surface.
That means Earth's water cycle may extend far deeper than the oceans, clouds, and rivers we see every day.
The planet beneath our feet may be storing an immense reservoir of water...
hidden inside rock...
hundreds of kilometers below us.
We usually think of Earth as having oceans on its surface.
But part of the planet's water may be hiding somewhere much deeper.
Not in an underground sea.
Not in a cavern.
But inside the minerals themselves.
There may be an ocean's worth of water hidden inside the Earth.
And we can only imagine what else is still down there.
Cut 05. 9:16. 149 seconds.
Get every episode summarized
Each time The Sound Around Us! publishes, we email you a written briefing from the transcript — the topics, who appeared, and any specific claims, with the ad reads skipped.
Email me new episodesFree for 3 shows. No card needed.
Hosts & guests
No transcript yet
This episode has not been transcribed. Request it and it moves to the front of the queue.
More episodes
More from The Sound Around Us!

The Bird Droppings That Made Nations Fight | The Guano Wars Explained
The Sound Around Us!

The Call of the Wild | Complete Audiobook | Jack London
The Sound Around Us!

Sound of Packing a Cardboard Box | Relaxing Packing & Moving Sounds
The Sound Around Us!

Let Another’s Loss Improve Your Preparation
The Sound Around Us!