How Submarines Dive, Steer and Stay Hidden Underwater

What is a submarine?

A sub is a boat that can travel alone below the sea ¹. It counts as an underwater vehicle and ship ². A submersible is different, with more limited range ¹.

Navy custom calls them boats, even huge ones ¹. Most big subs have a tube shaped hull ¹. The ends are rounded to handle water pressure ¹. A raised part sits near the middle ¹. It holds tools for talk, sensing, and seeing ¹. Americans say sail for this part ¹. Europeans say fin for this part ¹. A propeller or jet sits at the back ¹. Small fins there help with steering ¹.

How does it dive and rise again?

Diving is about float versus sink ¹. Tanks inside hold either air or water ¹. More water makes the boat heavier ¹. Then it sinks lower in the sea ¹. More air makes the boat lighter ¹. Then it floats back toward the top ¹. Small wings called planes also guide movement ¹. They tilt to point the nose down or up ¹. Forward motion plus tilt changes depth smoothly ¹.

The range of designs is very wide ¹. Small subs may carry one or two people ¹. They may stay down for a few hours ¹. Large subs may stay down for six months ¹. The Russian Typhoon class was the largest ¹. Subs can reach depths unsafe for divers ¹.

What is its history and use today?

Early plans date back to the 1500s ¹. William Bourne wrote a plan in 1578 ¹. John Napier wrote ideas in 1596 ¹. Cornelis Drebbel built a craft in 1620 ¹. It used oars for movement ¹. He served James I of England ¹. Nathaniel Symons made a ballast tank in 1747 ¹. It used leather bags filled with water ¹. David Bushnell built Turtle in 1775 ¹. It held one person and moved by hand ¹. It could move alone under water ¹. It used screws to push forward ¹. Robert Fulton built Nautilus for France in 1800 ¹. It used human power for movement ¹. France dropped the trial by 1804 ¹. Design grew fast in the 1800s ¹. Many navies then adopted subs ¹. Wide war use began in 1914 to 1918 ¹.

Today many navies use subs, big and small ¹. War roles include guarding ships and gathering facts ¹. They can also carry special forces in secret ¹. Civil roles include science and salvage work ¹. They help check gear under the sea ¹. Special subs help with rescue and cable repair ¹. Others serve tourism and sea history study ¹. Deep subs grew from the bathyscaphe design ¹. That design grew from the diving bell ¹. As of October 2026, more nations use subs ¹. China leads the new building surge ¹.