What If You Dropped a Steel Ball Into the Mariana Trench

It’s one of the most intriguing locations in the world. Covered in darkness and miles underwater, this extreme environment is home to some unusual creatures and phenomena. It’s called the Mariana Trench, and it’s the deepest oceanic trench on Earth.

No wonder it’s been so difficult to explore! Because of the risky conditions, people aren’t able to explore this location without proper equipment. But what would happen if we threw a steel ball down there?

Let’s start with some basics: how did they first discover this enormously deep hole in the ocean? HMS Challenger identified it back in 1875. The ship had some pretty fancy-sounding equipment for its time, but it wasn’t nearly good enough to be able to fully explore the trench.

Some decades later, in 1951, another ship, the HMS Challenger II came back to the location better equipped. The vessel featured an echo-sounder and was able to take accurate measurements of what seemed to be the deepest point on the surface of our planet. If you were to look at it in 2D, you’d see the trench measures 1,500 miles in length and 43 miles in width on average. It also looks sort of like a crescent-shaped scar when you observe it from above.

Nothing out of the ordinary so far, right? Well, if you were to stretch a wire from the surface of the ocean to the trench’s deepest point, it would measure a staggering 7 miles. If we were able to physically move Mount Everest — which is the Earth’s tallest mountain — to cover the Mariana Trench, it still wouldn’t be enough, falling short by about a mile.

Because the Mariana Trench is so deep, it’s almost completely covered in darkness as light can barely get through to such extreme distances underwater. The temperature isn’t any friendlier, either: just a few degrees above freezing. But the most dangerous feature of them all is the water pressure. Right at the deepest point of the trench, the amount of pressure is about a thousand times higher than the standard atmospheric pressure.

Not a lot of people ever attempted to descend in the Mariana Trench. In fact, the first organized attempt took place more than 60 years ago. It was done by Jacques Piccard and Don Walsh in a submersible. They only spent about five hours on their descent and a mere 20 minutes at the bottom. Alas, they weren’t able to take any pictures.

Until these two scientists were able to descend, specialists believed there was little to no chance that life could exist down there, given the conditions, most notably the extreme pressure. But while at the bottom, the submersible’s floodlight caught sight of a creature! It was a very flat one, indeed.

As you can imagine, resources here are very scarce. What kind of creatures live down here? And how do they survive, given the harsh environment? Surprisingly, there is quite an abundance of wildlife living in the Mariana Trench. Some of these creatures fall back on chemicals to survive, like methane or sulfur, while other kinds of fish nibble at the marine life that’s, well... weaker than them on the food chain.

The most common creatures found here are xenophyophores, amphipods, and small sea cucumbers. Some of them adapted by hardening up their shell, using aluminum harnessed from the seawater. Smaller creatures, like microbes, adapted by feeding on the chemicals emitted when the seawater hits the underwater rocks. They consider the Mariana snailfish the rockstar of the area in terms of wildlife. They’re small — ranging from 3 to 9 inches — translucent and lacking any scales, but they’re the top beast of prey in the area.

It’s no wonder some people started to believe that the ancient Megalodon might still be living here! What was a Megalodon, you might be wondering? It was the largest predator ever known in our planet’s history, basically the biggest and nastiest shark ever to have lived. Scientists believe it has been extinct for quite some time, and the idea that it might still be hiding in the Mariana Trench doesn’t have a lot of supporting information.

The Megalodon would have needed to learn to navigate in complete darkness. It would either have to be bioluminescent or evolve to have massive eyes. More so, because of its school bus-like size, the Megalodon would have needed a lot to eat. Microbes and small snailfish just wouldn’t have done the trick.

If a steel ball were to be dropped in the trench, what would be its effect on it? Would the ball be strong enough to sustain such pressure? Let’s look at the science here. If we assume it’s a solid steel ball, the pressure found at the bottom of the trench wouldn’t be enough to really affect it and cause permanent damage. It would take it a solid 12 minutes to reach the bottom of the ocean, though.

What about the temperature? Well, it turns out that the difference in temperature on the surface and at the bottom of the trench is quite impressive. So it would cause the ball to shrink a bit. But, yet again, once the ball returned to the surface, it would simply come back to normal.

Should the ball get stuck there, there’s another interesting question to answer: would corrosion affect it? Corrosion of steel is highly dependent on the amount of oxygen in the water. The amount of oxygen dissolved in water remains constant at depths greater than 3 miles. I’ll spare you the math, but it would take more than 10,000 years for the steel ball to completely rust under the sea.

I can’t help but wonder, though, what would it take us, humans, to be able to survive at such extreme depths? Let’s look at what was used in the past to explore this mysterious location: a little thing called syntactic foam. Why? Because it’s the only material that can both float and resist the amount of pressure found here.

Without this sort of protection, our lungs would rapidly collapse here. More so, the pressure from the water would push liquid into our mouths, replacing the much-needed oxygen with water. Then, there would be the much-needed ability to be able to come back to the surface should anything not go as planned.

One of the vessels that went for a deep dive here had 1,000-pound steel weights attached to it, so it would ensure its sinkage. These weights were connected to the ship by a special type of wire that had an increased corroding time of 11–13 hours in seawater just in case something went wrong down there, and they’d have to bounce back faster.

Given the harsh conditions here, the problem of oxygen supply is really important, too. Any vessel looking to descend into the Mariana Trench again would need to consider some sort of device that can recycle the air in order to reduce the amount of oxygen that needs to be transported down there.

And the last, but definitely not the least of all problems would be electricity! There surely isn’t a power socket down there for you to charge your phone. So there needs to be enough battery life to support all the necessary equipment: communication, oxygen supply, lighting devices, etc. None of these problems seem to be quite the challenge anymore since, as of recently, you can buy a tour of the Mariana Trench!

Three lucky individuals were part of such a project back in 2020. They were submerged in a 3.5-inch-thick titanium sphere. This ensured that they didn’t feel any pressure changes and any physiological stresses whatsoever. Each of the guests took part in an individual trip that had an estimated length of about 14 hours. The descent itself took over four hours. Once they reached the bottom, they got the chance to witness some of the most extraordinary creatures on the planet. Then, it was time to start the four-hour ascent back to the surface.