"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)

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.

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)

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)

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|

Episode Tone & Style

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

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.

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.”