They open valves to allow seawater to enter the ballast tanks outside.
The water would rush in and sink the sub. The pressure would equalise rapidly and when it does, the people inside would be crashed if they were too deep.
You drag the word "submarine" itself onto the submarine. Then you wait for it to sink.
The Confederate submarine 'H L Hunley' was the first submarine to sink an enemy ship
Submarines have ballast tanks inside them that can be filled with water to make them sink.
A submarine can sink and float in water because it has ballast tanks that can be filled with water to make it sink and with air to make it float. By adjusting the amount of water and air in the ballast tanks, the submarine can control its buoyancy and stay submerged at a desired depth or rise back to the surface.
A submarine is to spy on ship movements and if necessary sink ships
put the word submarine on it
A submarine
You grab the word submarine and pull it down.
You have to bring the word submarine down to the bottom of the screen.
The H. L. Hunley was the name of the Confederate submarine that was the first combat submarine to sink an enemy ship.
Filling the ballast tanks with water increases the submarine's density. This will cause it to sink into the water. Blowing out the water with air reduces it and the sub will return to the surface.