A submarine is a giant metal tube that can sink, swim, and resurface — all by changing its weight. How does it know when to sink and when to float? 🚢
The Magic of Ballast Tanks
Submarines have special tanks called ballast tanks. When the sub wants to sink, the tanks fill with water — making the sub heavy enough to go down.
When the sub wants to surface, compressed air pushes the water out of the tanks — making the sub light enough to float back up.
The Same Principle as a Fish
Fish do this with a special organ called a swim bladder. They add or remove gas to control their depth. Submarines work the same way — just with bigger tanks and water instead!
How Deep Can They Go?
🤿 Most military subs: 240–600 meters (about 2 football fields)
🤿 Deep research subs: 11,000 meters (the bottom of the Mariana Trench!)
Life Inside
Submarine crews can live underwater for months. Air is recycled. Fresh water comes from purifying seawater. Food is stored in huge freezers.
Imagine being underwater for 90 days without seeing the sun! That’s life on a nuclear submarine. ⚓
