HMS Nautilus was the largest submarine

Submarine

A submarine is a watercraft capable of independent operation below the surface of the water. It differs from a submersible, which has more limited underwater capability...

 built for the Royal Navy

Royal Navy

The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...

 at the time and the first to be given a name.

Nautilus was designed in response to recommendations for an overseas submarine displacing 1,000 tons and capable of 20 knots (39 km/h). The resulting design changed from the saddle tanks common at the time to a double hull.

The order was given to Vickers

Vickers

Vickers was a famous name in British engineering that existed through many companies from 1828 until 1999.-Early history:Vickers was formed in Sheffield as a steel foundry by the miller Edward Vickers and his father-in-law George Naylor in 1828. Naylor was a partner in the foundry Naylor &...

 in 1912 and her keel was laid down in March 1913. It took until 1917 to complete the vessel. Nautilus spent most of her life with the 1st Submarine Flotilla at Portsmouth

Portsmouth

Portsmouth is the second largest city in the ceremonial county of Hampshire on the south coast of England. Portsmouth is notable for being the United Kingdom's only island city; it is located mainly on Portsea Island...

as a depot ship and later as a battery charging vessel. She was renamed N1 in June 1917.