How Submarines Dive

Submarines can travel on the surface of the ocean and dive deep underwater. They control their depth using special tanks called ballast tanks. To dive, the submarine fills these tanks with water, making it heavier. To rise, it pushes the water out with compressed air, making it lighter.

Ballast Tanks

A submarine has ballast tanks between its inner and outer hulls. When the tanks are full of air, the submarine floats. To dive, valves open and water floods into the tanks. The submarine gets heavier and sinks. To come back up, compressed air is blown into the tanks, pushing the water out. The submarine gets lighter and rises.

Steering Underwater

Once underwater, the submarine uses fins called diving planes to steer up and down. Tilting these planes changes the angle of the submarine. A propeller at the back pushes the submarine forward. A rudder helps it turn left and right. Modern submarines can dive over 1,000 feet deep.

Fun Facts

• The deepest-diving military submarine can reach depths of about 2,000 feet.
• Nuclear submarines can stay underwater for months without coming to the surface.
• The first submarine was built in the 1620s and was powered by oars.

Did You Know?

Submarines make their own fresh water and oxygen while underwater. They use machines to remove salt from seawater and split water molecules to produce breathable oxygen for the crew!