"Yeah, that's a lot about Submarines, but not what I wanted to know!"

"Yeah, that's a lot about Submarines, but not what I wanted to know!"

This is how a submarine can dive and then surface.

Just like any boat, a submarine uses what is sometimes referred to as Archimedes' Principle, which is

"a body that is submerged into a fluid, loses exactly the same amount of weight, as the weight of the displaced fluid".

This means that a big heavy hollow boat loses a lot of weight when it is in the sea. What a submarine can do is change the amount of water it displaces. This is done by having a ballast tank which can be filled by water or air. Pressurized air is contained in another tank in the submarine.

• Fill the ballast tank with water - the submarine will sink.
• Fill the ballast tank with air - the submarine will rise.

                                                                                |   |                          | | |                        --------       Air tank        |        |             |         |        |             |         |        |    ---------|---------|        |------------------   /  |ooooooooooooooo|                            \  /    ---------------                              \ (                                                   )  \    _______________                              /   \  |wwwwwwwwwwwwwww|                            /    ---------X-----|-------------------------------             |     |                    |     -----------Ballast Tank             ---------Valve