For 17 hours, HMS Tireless was on top of the world – and the memories will linger long in the minds of the sailors who experienced it.

The hunter-killer submarine became the first British boat to visit the North Pole for eight years after surfacing with American nuclear submarine USS Hampton at the Earth’s most northerly point.

The few hours the two submarines spent on the surface, around half a mile apart, were the highlight of ICEX 04 – Ice Exercise 04 – which took nine months to plan and two months to execute as both countries’ Submarine Service brushed up on the special skills needed to guide a vessel through the high Arctic.

When Tireless broke through the surface of the Arctic ice, there was little more than a brief signal to confirm the fact that she had arrived at her planned destination, as the boat was still on patrol.

But now she is back in the UK, having hosted the crew of the Hampton in her home base of Devonport, the crew have been talking about the experience.

If there’s one thing which is predictable about the North Pole it’s that it’s unpredictable - a constantly changing environment which brings new challenges at every turn.

“Areas of thin ice or open water within the pack ice, known as polynyas, are constantly mapped using upward-looking cameras and ice-avoidance sonar,” said Lt Christopher Morgan, the boat’s Public Relations Officer.

“That provides the submarine with the most up-to-date information, otherwise the ice cap is as hard as steel, forged from thick sheets of huge ice boulders which are impossible to penetrate.”

Any data more than a few hours old is unreliable, but beyond the technical wizardry on board the Trafalgar-class submarine, Tireless also had a specialist ‘ice pilot’, Barry Campbell from the US Arctic Submarine Laboratory - based in the incongruously-sunny surroundings of San Diego.

Barry had made seven previous trips to the top of the world on British and American boats, and provided invaluable advice to Tireless’ Commanding Officer Cdr Phillip Titterton on how to avoid the deep ice ‘keels’ which can extend up to 60 metres – 200 feet – below the surface of the water.

Once on the surface, the crew had to find suitably thick ice to support Tireless’ portable brow so they could ‘run ashore’, and a sentry was posted to look out for polar bears.

Temperatures hovered around the –23°C mark, despite the region being bathed in glorious sunshine for much of the submarines’ visit.

The two crews found time for a brief kickabout on the ice – the much-anticipated football match could not be organized as a flat, clear pitch could not be created amongst the ice boulders - while Cdr Titterton presented submariners’ dolphins to STD Tom Bell, sonar operators Tim Ezared and Paul Hoodless, and MEMs Daniel Light and Chris Lloyd-Stafford, before the hatches were closed and the boats disappeared beneath the ice again.

“It may have been just ice, water, sun and sky, but the polar environment has a magical quality that will leave an indelible impression on those fortunate to have made it to the top of the world,” said Cdr Titterton.

Going to the top of the world is more than a PR exercise.

The Arctic remains an important operational environment for British and American submarines, although it is eight years since the two nations last operated together under the Pole, and 13 years since Tireless visited the top of the world, on that occasion accompanied by USS Pargo.