In pictures: Commandos hitch a ride on a submarine through the icy fjords of Norway

Whether yomping across long distances, fast-roping from helicopters, or inserting onto beachheads in small raiding craft, personnel from 3 Commando Brigade have perfected the art of covert movement and stealthy insertion.

Deep inside the Arctic Circle, this core principle of their operational doctrine would see Royal Marines and Commandos from 29 Regiment hitch a ride on a German U-35 attack submarine.

It offered a discreet means of deployment while underscoring the commando force's role as the tip of the spear in one of Nato's most strategic regions on earth.

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Conducted by elements of the Commando Force, the Surveillance and Reconnaissance Squadron (SRS), Shore Reconnaissance Troop (SRT) and 148 Commando Forward Observation Battery, the mission was clear. 

Slip in unseen and remain hidden while surveying enemy positions, calling in naval gunfire from allied warships before making a stealthy getaway.

Second in command of SRS, whose identity cannot be revealed for operational reasons, said: "In the High North's harsh and unforgiving domain, where extreme climatic conditions and adversary vigilance dominate, the ability to covertly insert reconnaissance teams ashore via Inflatable Raiding Craft (IRC) launched from a submarine is indispensable.

"It delivers the stealthy edge needed to penetrate denied areas, deny the enemy sanctuary, collect vital intelligence on subsurface and littoral threats and shape the operational environment before any escalation."

For SRS and SRT, who have long operated at the very tip of the Royal Marines' spear, conducting these kinds of operations ahead of the main allied force has become second nature – whether carrying out raiding, reconnaissance, or surveying missions.

Meanwhile, 29 Commando's 148 Battery are specially qualified in calling artillery, naval gunfire control and airstrikes to support the Commando Force and UK Special Forces. 

They are experts in covert insertion, patrols behind enemy lines, concealment, encrypted communications and battle damage assessment.

A Team Leader from 148 Battery said: "We regularly train with Nato Special Operations Forces partners to practise naval fire support, but it's been great getting re-qualified in this insertion method.

"Serials like this are similar to our historical roots, dating back to the Falklands, where 148 delivered naval gunfire prior to the retaking of the islands. Combining naval gunfire support with this is a key skill to support operations in the High North."

This training forms part of the UK deployment to the Arctic Circle, which has seen around 1,500 commandos operating in Northern Norway since January. 

It is all in the build-up to the Norwegian-led Exercise Cold Response, which is aimed at the defence of the alliance's northern flank.  

All images courtesy of the MOD.