How are Submarines able to dive under the water?

Summary

"Who Smarted?" – How are Submarines able to dive under the water?

Podcast Episode Summary
Date: September 29, 2025
Hosts: Trusty Narrator (A), Professor Briney (B), Meatcake Lady (C), Ad Reader (D)

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Main Theme / Purpose

This episode of "Who Smarted?" takes young listeners on an imaginary descent aboard the Deep Sea Challenger to explore the fascinating world of submarines. Through humor, story-driven dialogue, trivia, and sound effects, hosts Trusty Narrator and Professor Briney explain how submarines dive, how they maintain underwater life support, and the evolution of submarine technology. The episode combines STEM learning with laughs to demystify the science behind these remarkable underwater vessels.

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Key Discussion Points and Insights

1. Setting the Scene: Deep Sea Adventure

• [00:02] Listeners are welcomed "10,000ft below the ocean" aboard the Deep Sea Challenger.
• Introduction of Professor Briney, an engineer specializing in underwater vehicles.
• The goal: Use this journey to learn about submarine technology, history, and science.

2. History and Evolution of Submarines

• [03:40] When was the submarine invented?
  • "If you said the 20s, you're right, kind of, because you're probably thinking of the 1920s, but it's really the 1620s." (A, 03:48)
• [04:07] Submarine’s military debut:
  • Revolutionary War’s "Turtle" by David Bushnell.
  • The Civil War's "Hunley," which managed to sink a ship and itself.
• Early submarines had limited success; their designs were primitive and risky.

3. How Submarines Dive and Surface: The Science of Buoyancy

• [05:47] Buoyancy and Ballast Tanks Explained
  • “A submarine is able to control its level of buoyancy by using its ballast tanks.” (B, 05:48)
• [06:05] Ballast tanks can be filled with air (float) or water (sink); submersibles use heavy weights.

4. How Long Submarines Can Stay Underwater

• [06:51] Trivia: “How long can a submarine stay underwater? A) one day, B) three months, C) 25 years?”
  • Early subs (diesel) surfaced daily for oxygen.
  • Modern (nuclear-powered) subs could technically stay submerged for up to 25 years—but only have enough food for about 90 days.
• [08:13] “Submarines only have so much room to store food. Usually enough to last about 90 days or three months.” (B, 08:16)

5. Oxygen, Air Supply, and Life Support

• [09:00] Very few windows: primarily so they don’t break under extreme pressure.
• [09:17] “As we go deeper and deeper under the ocean’s surface...the pressure...could instantly crush our submersible. Like an aluminium can, or do you say aluminum?” (B, 09:20)
• [10:21] How Submarines Get Fresh Air
  • Electrolysis splits water (H₂O) into hydrogen and oxygen for breathing.
  • CO₂ scrubbers remove carbon dioxide.
  • “By adding oxygen and removing carbon dioxide, you now have a breathable underwater environment.” (B, 11:15)

6. Fresh Water Supply (Desalination)

• [11:43] Submarines convert seawater to drinking water via "desalination,” specifically by boiling and distilling seawater.
  • “They can churn out 40,000 gallons of fresh water a day on a submarine.” (B, 12:41)

7. Depth Limits of Submarines

• [12:49] Deep Sea Challenger—as a special submersible—can go deeper than regular submarines.
• Most nuclear subs: safe depth is about 200 meters (600ft), with maximum depths up to 300 meters (over 900ft).
  • "But it's certainly not advisable." (B, 13:35)

8. How Submarines Navigate: Sonar

• [13:40] INTRO TO SONAR: "Sonar, spelled S O N A R, stands for sound navigation and ranging." (B, 13:43)
• [15:23] Sonar is used primarily to avoid obstacles and locate targets.
• [15:47] “Our sonar emits a pulse of sound into the water and listens for it to echo back...we can use the amount of time it takes to rebound to calculate how far away an object is.” (B, 15:47)
• [16:22] Sound travels roughly 3,000 mph underwater (approx. 1 mile/second).

9. Undersea Dangers and Finale

• [16:52] Encountering hydrothermal vents (underwater volcanoes)—dangerous due to superheated water.
  • "The superheated water coming out is 700 degrees. It could melt the window of our submersible." (B, 17:06)
• [17:22] They escape by releasing weights and rising via buoyancy.
• Wrap-up with a humorous callback: “Volcanoes give me gas.” (C, 17:47)

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Notable Quotes & Memorable Moments

• On Submarine History:
  • “It was designed to secretly place explosives on the outside of British ships...Naturally, General George Washington loved this idea.” (A, 04:24)
• On Buoyancy:
  • “When you want a submarine to float on the surface, you fill its ballast tanks with air...when you want it to go underwater, you need to push the air out...and fill them with water instead.” (B, 06:05)
• Food Storage Reality:
  • “Submarines only have so much room to store food. Usually enough to last about 90 days or three months.” (B, 08:16)
• Comic Relief:
  • “I brought you some meat cake. I sampled a little. Okay, a lot, but it's delicious.” (C, 08:41)
• Oxygen & Pressure Danger:
  • “If something went wrong, all that pressure could instantly crush our submersible. Like an aluminium can, or do you say aluminum? An aluminum can.” (B, 09:20)
• On Fresh Air:
  • “They're actually able to separate the hydrogen and oxygen molecules by passing electrical current through purified seawater. This process is called electrolysis.” (B, 10:58)
• How Sound Travels Underwater:
  • “The answer is roughly 3,000 miles per hour, or about 1 mile per second.” (B, 16:22)
• Hydrothermal Vents:
  • “The superheated water coming out is 700 degrees. It could melt the window of our submersible, and then we'd be…” (B, 17:06)

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Timestamps for Key Segments

| Topic/Section | Timestamp | |------------------------------------------------|------------| | Welcome, setting the scene | 00:02 | | Meet Professor Briney, intro to submarines | 00:34 | | Submarine history & first uses | 03:40–05:47| | Buoyancy & ballast tanks explanation | 05:47–06:50| | How long can submarines stay underwater? | 06:51–08:16| | Life support: oxygen, CO2, air | 10:21–11:43| | Water purification/desalination | 11:43–12:44| | How deep can submarines go? | 12:49–13:37| | Sonar introduction & how it works | 13:40–16:12| | Underwater hazards: Hydrothermal vents | 16:55–17:36| | Episode wrap-up & humorous moment | 17:36–17:47|

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Episode Tone & Style

• Playful, humorous, and accessible.
• Regular direct address to the child listener (“Smarty Pants”).
• Engages through interactive trivia and silly answers/banter.

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Brief Takeaways

• Submarines descend and ascend by manipulating ballast tanks with air or water.
• Earliest subs date back over 400 years; modern nuclear subs can, in theory, stay underwater for years, but food is the limiting factor.
• Oxygen is produced on board from water via electrolysis, and CO2 is scrubbed out.
• Drinking water is produced by desalinating seawater through distillation.
• Regular subs have strict depth limits to avoid extreme pressure; only specialized submersibles reach deep ocean trenches.
• Sonar (sound navigation and ranging) helps avoid obstacles by bouncing sound off underwater objects.
• Dangers include high pressure, limited food, and underwater volcanoes.

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This episode makes learning about submarine science and history fun and digestible, blending solid STEM concepts with jokes and story. Even adults will find themselves sticking around for the undersea adventure—and maybe even for a slice of “meat cake.”

Transcript

[A]

Oh, hey, smarty pants. Trusty narrator here. Glad you could meet me 10,000ft below the ocean surface. Oh, did you not realize you were over two miles deep in the ocean? Well, you are. In fact, thanks to the magic of podcasting, we're all crammed inside the Deep Sea Challenger, which is a high tech underwater vehicle known as a submersible. Um, professor, you might want to take a hard left and dodge that giant squid.

[B]

Oh, good call, trusty narrator.

[A]

Smarty pants, please say hi to Professor Briney. She's an engineer who knows all about underwater vehicles like this one. She's my partner today as we ride the Deep Sea Challenger to the bottom of the Mariana Trench, the deepest part of the Pacific Ocean.

[B]

Hi there, smarty pants. Thanks for joining us as we make our way 35787fe down into the ocean. That's almost seven miles.

[A]

Whoa.

[B]

It'll take us about two and a half hours to get all the way down to the bottom.

[A]

Yep, and wouldn't you know it, I forgot to bring a book. So, smarty pants, I figured I'd pass the time by telling you all about the underwater vehicle that made this super high tech submersible possible. The submarine.

[B]

And I'm happy to help too. After all, the submarine was a pretty tricky invention for humans to figure out. But ever since they did, they'd sure come in handy. From exploring the ocean's depths, to helping recover lost items from shipwrecks, to their role in combat missions. They can even launch nuclear weapons. But of course, hopefully they never will.

[A]

Good points, Professor. And despite it being incredibly cramped in here, this is the perfect place to take a deep dive on submarines and learn things like how do they make themselves sink? How long can they stay underwater? And how does a submarine's crew get fresh air to breathe? Get ready for another whiff of history and science on who's smarted?

[C]

Who's smarted? Who's smart? Is it you? Is it me? Is it science or history? Listen up, everyone. We make smarting lots of fun. On who's smart?

[A]

And you know, when I was a.

[D]

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[A]

Quick question, smarty pants. When do you think the invention of the submarine happened? In the 20s? The 30s, or the 40s? If you said the 20s, you're right, kind of, because you're probably thinking of the 1920s, but it's really the 1620s.

[B]

That's right. Trusty inventors were testing primitive versions of submarines for over 400 years.

[A]

Another quick question, Smarties. Which was the first war where a submarine was used? Was it the American Revolutionary war, the American Civil War, or World War I? Believe it or not, it was the American Revolutionary War. In 1776, a man named David Bushnell built a small, round wooden submarine that could only hold one person, and he called it the Turtle. It was designed to secretly place explosives on the outside of British ships, causing them to sink. Naturally, General George Washington loved this idea. Unfortunately, the ship carrying the Turtle out to sea sank to the bottom of the ocean before the Turtle could ever be used. Whoops. But they did give submarines another try. In the Civil War, a Confederate army sub called the Hunley was made out of bulletproof iron and could hold up to eight soldiers. It was powered by a hand crank. However, the Hunley didn't fare much better. While its crew did manage to sink one Union ship with a torpedo, they wound up sinking themselves in the process. And the Hunley joined the Turtle at the bottom of the se. Okay, so submarines clearly got off to a less than stellar start. But let's back up, Professor. How are things supposed to work? For starters, how do submarines make themselves sink intentionally?

[B]

The secret is something called buoyancy. The more buoyant something is, the more likely it is to float. A submarine is able to control its level of buoyancy by using its ballast tanks.

[A]

I see. And ballast tanks are.

[B]

A ballast tank is a compartment in a boat, ship, or floating device that's designed to hold water. When you want a submarine to float on the surface, you fill its ballast tanks with air. That makes the sub less dense than the water around it, so it floats. But when you want it to go up underwater, you need to push the air out of the tanks and fill them with water instead. That makes the submarine more dense than the surrounding water, so it sinks. The submersible we're in right now works the same way, but uses heavy weights instead of water.

[A]

Ah, just like me at the gym. Okay, so let's say a submarine does go underwater. How long can it stay under before it needs to surface again? What do you think, smarty pants? Is it A, one day, B, three months, or C, 25 years?

[B]

Well, that's kind of a tricky question, Trusty. You see, America's submarines used to run on diesel power. And diesel engines need oxygen, so those subs have to surface nearly every day to get air. But in 1954, they launched the first nuclear powered sub called the Nautilus. And today, all of our submarines are nuclear powered. Nuclear engines don't need oxygen. So theoretically, those subs could stay underwater for 25 years.

[A]

Whoa. Ah. So do most submarines stay down for that long?

[B]

No, because submarines also run on a different kind of fuel. It's a special combination of Twinkies, hot dogs, chicken, chips, a fruit or vegetable veg, maybe even.

[A]

Oh, you mean food for the crew.

[B]

Exactly. Submarines only have so much room to store food. Usually enough to last about 90 days or three months.

[A]

Aha. So, smarty pants, if your answer to my previous question was three months, congrats. But technically, the other two answers were also kind of right. Professor, did you just.

[B]

No, that wasn't me.

[C]

Sorry. That was me. Trusty. I thought you might get hungry, so I brought you some meat cake. I sampled a little. Okay, a lot, but it's delicious.

[A]

Thanks. I'll have some later. But now it smells pretty bad in here. I'd open a window, but I don't think that's a good idea.

[B]

No, that's a very bad idea.

[A]

Why do we have just one tiny window? Care to guess, smarty pants? Is it because, A, there's nothing to see, B, a window might break, or C, windows are annoying to clean?

[B]

The answer, of course, is B, they might break. As we go deeper and deeper under the ocean's surface, our submersible, just like a submarine, is under more and more pressure. In fact, when we get to the bottom, the pressure on the outside of our craft will be 1,000 times more than we started. If something went wrong, all that pressure could instantly crush our submersible. Like an aluminium can, or do you say aluminum? An aluminum can.

[A]

I wish you hadn't told me that.

[B]

It's okay. You're safe. Underwater vehicles are made from super strong materials like titanium and steel.

[A]

Not much glass, but meatcake lady brought up an interesting point I did. Spending three months in a confined space with a hundred other crew members could get pretty stinky.

[C]

Oh, I get it.

[A]

Not to mention, wouldn't they run out of oxygen? Where do submarine crews get fresh air to breathe?

[B]

Well, one thing people on a submarine have plenty of access to is water. As in seawater. And water is a combination of hydrogen.

[A]

And oxygen, which is why we call water H2O.

[B]

Exactly. The H stands for hydrogen and the O for oxygen. So the trick is figuring out how to get the oxygen out of the water so the crew on the submarine can breathe it.

[C]

That I don't know.

[A]

Me neither. Luckily, there's a professor on board.

[B]

They're actually able to separate the hydrogen and oxygen molecules by passing electrical current through purified seawater. This process is called electrolysis.

[C]

Oh, sounds complicated. Unlike my recipe for meat cake, which is just meat and cake.

[B]

But wait, there's more. Submarines also have devices on board called CO2 scrubbers. These scrubbers use chemicals to remove carbon dioxide the crew members exhale. By adding oxygen and removing carbon dioxide, you now have a breathable underwater environment.

[A]

Wow, what a marvel of science. Okay, so we've talked about the food and air on submarines, but what about drinking water? Everyone knows you can't drink ocean water because of all the salt.

[B]

You're right. But luckily we know how to take the salt out of it.

[A]

What do you think, smarty pants? Do they remove the salt by freezing the salt water, boiling the salt water, or politely asking the salt to scram? The answer is boiling.

[B]

Or what we call desalination. On board every submarine is a distillation plant where seawater is heated until it becomes steam that removes all the salt. That steam is then cooled, which turns it back into water. Only now it's fresh water you can drink. They can churn out 40,000 gallons of fresh water a day on a submarine.

[A]

Wow. Submarines definitely have come a long way since the turtle.

[B]

Speaking of a long way, we're now around 34,000ft deep.

[A]

Speaking of, we're in a special submersible submarine which allows us to go this deep. But a regular nuclear submarine can't go this deep, right?

[B]

Oh, no, not even close if it tried.

[A]

So, smarty pants, how deep can a submarine go? Normally, I'd do a Multiple choice answer. But for this, there's actually multiple answers. Right, Professor?

[B]

Yes, with most nuclear subs, you don't want to go any further than 200 meters or 600ft down. But subs have been known to go 300 meters or over 900ft down, and some have gone even further down. But it's certainly not advisable.

[A]

Um, what's that?

[B]

Our sonar.

[A]

Oh, good. Um, what's sonar?

[B]

Sonar, spelled S O N A R stands for sound navigation and ranging.

[A]

Oh, is that how a submarine knows where it's going?

[B]

It can definitely help, but that's not the main reason submarines use sonar.

[A]

Yikes. Sounds like the sonar is trying to tell us something. We'll find out what it is and what sonar does right after this quick break.

[D]

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[A]

Now back to whosmarted. Professor, what's going on? What is the sonar telling us? Smarty pants? Do you know?

[B]

Well, sonar tells us two important things. Number one, whether we're going to run into something. And two, if you're in a combat situation, how far away your target is.

[A]

What is it saying now?

[B]

It's nothing to worry about. Just some sea cucumbers ahead.

[A]

Phew. So how does sonar work?

[B]

You hear those pings? That's our sonar emitting a pulse of sound into the water and listening for it to echo back. Because we know how fast sound travels through water, we can use the amount of time it takes to rebound to calculate how far away an object is.

[A]

Smarty pants Any idea how fast sound travels through water? Is it 1,000 miles per hour, 2,000 miles per hour, or 3,000 miles per hour?

[B]

The answer is roughly 3,000 miles per hour, or about 1 mile per second.

[A]

Aha. So sound travels through water at one mile per second, and it takes five seconds to hear the echo. Then that object is. Did you say about five miles away, Smarty pants. Great job. If you got that.

[B]

Some animals, like bats, whales, and dolphins use a version of animal sonar called echolocation.

[A]

Um, professor, more cucumbers?

[B]

No, we're getting close to something near the ocean floor. Ah, I see it. It's a hydrothermal vent.

[A]

Is that good?

[B]

No. Hydrothermal vents on the openings of underwater volcanoes. The superheated water coming out is 700 degrees. It could melt the window of our submersible, and then we'd be.

[A]

Oh, boy. What do we do?

[B]

Surface. Quick, release the weights. The natural buoyancy of the submersible's foam body will lift us back to the surface. It'll take a while, but we're safe.

[A]

Phew. That was close. Well, thank you, Professor. We sure learned a lot of cool stuff about submarines.

[B]

My pleasure, Trusty.

[A]

Oh, no, not again.

[C]

Sorry. Volcanoes give me gas.

[A]

A special shout out to CC In New Hampshire. You told us who Smarted is your.

[D]

Go to podcast that we help you learn so much. Well, Cici, that makes you a top.

[A]

Tier smarty pants in our book. Thanks for listening. This episode Submarines was written by Steve Submariner Melcher and voiced by Emma Wilson, Adam Das Boot Davis and Jerry Colbert. Technical direction and sound design by Josh Hunt for Red October Khan who Sparted is recorded and mixed at the Relic Room Studios. Our associate producer is Max Crimson Tide Kamasky. The theme song is by Brian Upscope Suarez with lyrics written and performed by Adam Tex Davis. Who Smarted was created and produced by Adam Tex Davis and Jerry Colbert. This has been an Atomic Entertainment production.