How do submarines sink and float?

Sean and Robot are learning about submarines – how they go down… and come up again!

To sink, a submarine must weigh more than the water it displaces – this is called a negative buoyancy. So to get it to weigh more, special tanks are flooded with water. This makes the sub heavier and so down she goes.

And when they want to go up, they need to make the sub lighter. So they pump the water out of the tanks, replacing it with air. The sub gets lighter and is able to surface.

There’s tons of cool technology that help subs work – even at two kilometres under the surface of the water. Thick double hulls keep the pressure comfortable inside. They’re made of tough materials, such as titanium or steel.

And because they might be a long way away from shore, many of them even make their own power on board.

Fins on a submarine work a bit like wings to help steer these enormous beasts, along with propellers which push it through the water.

Submarines use soundwaves that travel through the water – if there’s an obstacle ahead, the soundwaves come back and they can figure out how far ahead the object is. It’s called Sonar.

Click here to get Sean’s Ships on iTunes!

Get the series on your phone or tablet and listen whenever you like – at home, in the car or onboard your very own ship!

Find out how huge, heavy container ships manage to float on the water and how submarines can go for months and months sitting at the bottom of the ocean!

You can hear new episodes weekdays from 8am on Fun Kids – and catch-up on previous episodes in full now!

You can subscribe to the Sean’s Ships podcast channel for FREE in:

…or you can listen here: