Dive! Dive! Dive! Find out how the Silent Service has evolved over the past 125 years

Hidden deep below the surface, the Royal Navy's submarines are the most powerful stealth weapons of war ever built by Britain.

The men and women of the Silent Service operate unobserved, undetected and ready to unleash a destructive power greater than ever before.

But how did we get here? To answer that we need to dive down though the decades, back to the start of the last century – back to where the future of underwater warfare began.

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Where it all began

The Royal Navy first truly began to embrace submarine technology in 1901, with the petrol-driven Holland 1.

She had a crew of nine, one 18-inch torpedo tube and three torpedoes.

This was the first true incarnation of a metallic, manned underwater stealth weapon, designed to stalk and destroy its prey.

So what allowed it to rise from the depths of this first design to today's largest submarine – the UK's nuclear-powered ballistic missile-carrying Vanguard class?

The answer is the advance of time and technology.

These have seen a submarine with a submerged displacement of 107 tonnes turn into one with a displacement of 15,900 tonnes.

And while the Holland 1's first venture beneath the waves had a range of 20 nautical miles, today's nuclear-powered submarines are unlimited, save for the need to rotate crews and replenish supplies.

Six steps to success

So what big technological advances have driven the development of the submarine? Here are my top six:

Propulsion

Petrol was replaced by diesel electric from the early 1900s right up to the 1950s, when nuclear power entered the equation.

This paved the way for today's continuous-at-sea deterrent and limitless-range attack submarines.

Pressure hulls

At the same time the thin steel hulls of those earliest submarines, held together with rivets and then welding, evolved as higher-strength steels, advances in metallurgy and the birth of nuclear power drove the creation of ever-stronger, more resilient pressure hull designs.

Sensors

Another remarkable evolution has been submarine sensors – starting out as the hydrophone – a mechanical underwater microphone triggered by sound wave, then becoming the precursor to sonar – the ASDIC, generating a ping that's reflected back by a contact.

This led to the rise and use of submarine active and passive sonar technologies that have gone from "I can locate you with echo" to "I can identify you using your acoustic signature" and now "I can build an acoustic picture of the entire battlespace without transmitting".

Today's submarines are festooned with technology around the hull to collect this information.

And quantum sensors, which are currently in development, will change the playing field again, reportedly detecting the tiniest changes in magnetic fields or gravity with big implications for underwater cat-and-mouse encounters.

Periscopes

Even that most famous of submarine icons – the optical periscope, with its hand grips and rubber eye guard for the captain made famous in the movies – has since been replaced by non-penetrating optronic masts, using high-definition thermal, infrared and digital cameras.

Navigation

And let's not forget the huge major leaps in navigation. What began with dead reckoning – working out where you were from where you started – soon advanced through the use of sonar mapping and gyroscopes to the systems operating on today's most advanced submarines like HMS Vanguard.

These combine laser gyroscopes and gravity gradiometry to avoid the need to come shallow to correct errors using stars and satellites by reading the Earth's magnetic field variations, with quantum initial navigation systems allowing even greater accuracy.

Weaponry

Those advances in technology and materials have seen today's submarines go deeper, faster, further and for longer than ever before.

And they are also far more deadly.

The Astute class – Britain's main nuclear-powered attack sub – packs a punch with Tomahawk IV land attack cruise missiles.

Back in 2013 our cameras were allowed rare access inside HMS Ambush. She's the second of seven – her sisters being HMS Astute, Artful, Audacious, Anson and Agamemnon, with HMS Achilles under construction.

But it's the Vanguard class, with a crew complement of 132, that is the UK's primary defensive weapon with its long-standing nuclear strike missile system, Trident. 

The way ahead

So what does the future hold for the Royal Navy's Silent Service?

Well, there's the Dreadnought class submarine programme.

HMS Dreadnought, the first in class of four new ballistic missile nuclear submarines, is expected to complete her sea trials and be ready to enter service with the Royal Navy in the early 2030s, followed by HMS Valiant, HMS Warspite and HMS King George VI.

Each will be 153.6 metres long – about the length of three Olympic-sized swimming pools – and will even have separate female crew quarters and facilities.

And – as the replacement for the Vanguard class – they will carry the Trident missile system.

Also on the way is the SSN Aukus – a future class of conventionally armed, nuclear-powered attack submarines under shared development between the US and Australia for the Royal Navy and Royal Australian Navy.

Built in the UK and Australia, the first of the 12 UK submarines will be delivered in the late 2030s to replace the current Astute-class vessels, and the first Australian submarines will follow in the early 2040s.

But lurking beneath the surface of the future of the submarine is also the age of the autonomous unmanned submarine.