Technology
How does a submarine work?
A submarine works by changing its weight to dive and surface, using tanks that fill with water or air. To dive, it floods ballast tanks with seawater to become heavier; to surface, it blows the water out with compressed air to become lighter.
See it in motion.
Watch a 2-minute animated lesson that shows exactly how a submarine works.
Step by step
- 1Ballast tanks fill with water to make the sub heavier and sink.
- 2Compressed air pushes the water out to make it lighter and rise.
- 3Adjusting the balance lets it hover at any depth.
- 4Propellers and fins drive and steer it underwater.
- 5It carries its own oxygen and can stay submerged for long periods.
Frequently asked questions
- How does a submarine dive and surface?
- It floods ballast tanks with seawater to get heavier and sink, then blows the water out with compressed air to get lighter and rise.
- How does a submarine stay at a set depth?
- By balancing its weight against the water it displaces, fine-tuned with ballast and small 'trim' adjustments, so it neither rises nor sinks.
- How do submarines get air to breathe?
- They carry oxygen supplies and systems to scrub carbon dioxide; nuclear subs can even make oxygen from seawater, staying down for months.