Our missing map of the ocean explained.

Isn’t the ocean already mapped? Nope. 85% nope. (Part 1 of 3)

It’s the most obvious question we’re asked. It’s almost unfathomable and unbelievable when people hear we haven’t actually mapped much of the ocean. “What about Google Earth,” they say.

“What about this?”:

Google Earth

At a planetary scale, yes — it certainly does look mapped.

Let’s zoom into the middle of the ocean…. to the same scale you’d look at perhaps a large mountain range. Below is the mid-Atlantic ridge, an area we’ve spent a lot of time trying to map in “high-resolution” (50–100m). You can see the ridge is pretty detailed and quite large.

Google Earth — Mid Atlantic Ridge

In fact, it looks just like a substantial mountain range. Because it is.

For scale comparison of the image above, see the image below of the rocky mountain range and Denver, CO on the same scale.

Google Earth — Denver, CO, and the Rocky Mountains.

To see them together:

Comparison of the two.

Now, look at the “blurry patches” to the left of the ridge in the ocean image above. There’s a crazy difference in resolution, even in this one frame of the ocean we care a lot about.

This is where the problem comes in and can be seen.

85% of the ocean we’re missing mountain ranges, ravines, and any sort of detail. It’s blurry, obscure, without any idea what’s actually going on, or what it looks like. We only know extremely large pronounced features that can be seen at a 0.5–5km resolution.

Take a look below. I zoomed in to a random area and found 2 ship tracks peppered amongst a blurry region.

Google Earth — somewhere in the Atlantic Ocean, West of the Mid-Atlantic Ridge.

What’s going on? Why is that?
85% of the ocean is “mapped” with a technique called satellite altimetry. Essentially satellites are measuring micro-changes in the Earth’s gravitational field above the ocean and then inferring the thickness of Earth’s crust below.

When you see this resolution at planetary-scale, it looks like we know what’s there:

But we don’t.

GEBCO — comparison of what 85% of the ocean is like (left) to what it looks like when you map with modern sensors (right). The grand canyon averages 16km wide. Manhattan is 3.7km wide at it’s widest point.

At this resolution we’d miss the pyramids at Giza, NYC, the Great Wall of China, most smaller mountain ranges like the white mountains and would have no understanding of the true size of the Grand Canyon.

Google Earth — The Grand Canyon

What this means is that our understanding of most of the ocean floor is purely inferred.

It also means the best resolution we’re going to get is 0.5 km (physics limit) with satellite altimetry techniques. The inherent error in these inferences is ± 1km up and down. That’s 2km of vertical play in our understanding of how the ocean floor exists for 85% of the whole thing. On top of that, the data is “smoothed out” creating the blurry surface that makes up the majority of the ocean map we have.

Google Earth — somewhere in the Atlantic

The only way we can verify ground truth is actually going down with sonars and measuring it over each point, which is obviously quite hard to do with oceans as large as ours.

To get a better sense of what we do know, let’s take out all the inferred satellite altimetry data and color it black.

We get this:

GEBCO / CCOM — for a globe view.
GEBCO / CCOM — for a Mercator projection view.

The black areas represent no data.
The black represents 60% of the earth.

That’s 118.14 million mi² or ~ 2x the surface area of Mars.

Why can’t we predict hurricanes, and tsunamis very well? The black area.
Why can’t we find flight MH370? The black area.
Why do we need to run expensive subsea surveys anytime we want to do scientific, commercial, engineering, government, military, or energy projects in the ocean?

That. black. area.

The largest Earth exploration mission in human history will be required to begin understanding that black area. Much more to come on how we plan to do that.

This is Part 1 of 3 in a series written to understand the ocean mapping problem better.

Part 2 of 3 will dig into how we acquire mapping data in the ocean, which will explain why to date there is so much unknown information. Part 3 of 3 is digging into what should a map of the ocean actually include, and what it would mean to science, business, government, and militaries if we could collect it all.

If you found this interesting, please give it a clap or two and please, please please share. If you want this in your inbox, feel free to sign up here.

--

--

Get the Medium app

A button that says 'Download on the App Store', and if clicked it will lead you to the iOS App store
A button that says 'Get it on, Google Play', and if clicked it will lead you to the Google Play store