The vessel involved was the HMS Astute, one of Britain’s fleet of submarines powered by nuclear reactors and launched in 2007. The 328-foot-long vessel grounded on rocks off the Isle of Skye, off the west coast of Scotland.

“This is a not a nuclear incident,” Britain’s defence ministry said in a statement. “We are responding to the incident and can confirm that there are no injuries to personnel and the submarine remains watertight. There is no indication of any environmental impact.”

Another spokesman with the ministry said the vessel had “grounded a rudder” at Kyle of Lochalsh near the Isle of Skye shortly after 8 a.m. local time. No other vessels were involved.

The submarine will be floated at the next high tide, which is due at around 6 p.m., he said.

Defence workers were at the scene to assist the submarine’s crew, the ministry said. The submarine is armed with Spearfish torpedoes and Tomahawk cruise missiles. It is powered by a nuclear reactor that will never need refuelling during in its 25-year operational life, according to the ministry.

A crew of around 100 are typically aboard the ship.

Astute, which was commissioned into the Royal Navy on August 27, is “the U.K.’s most powerful attack submarine,” the ministry said on its website. It is quieter than other submarines in the fleet, even though it is 50 percent bigger, and can circumnavigate the world without surfacing.

“A highly complex feat of naval engineering, she is at the very cutting-edge of technology,” First Sea Lord Admiral Mark Stanhope said on August 27, adding that Astute would undergo a “series of demanding seagoing trials testing the full range of the submarine’s capabilities.”

The Marine and Coastguard Agency has sent a tug to the scene to help with the salvage operation, which is being led by the navy, MCA spokesman Mark Clark told the Bloomberg news agency.

Another British submarine, HMS Trafalgar, was damaged when it ran aground during a training exercise in November 2002. An inquiry found the incident was a result of “human error.”

There has been no word yet from the British authorities as to the cause of the grounding, which they said was under investigation.

Alexander Nikitin, chairman of the Environmental Right Centre (ERC) Bellona, and a former submarine captain in the Russian Navy, said that navigational errors are common aboard submarines and can lead to groundings.

“Navigation-related accidents at sea are, in a way, common occurrences not unlike those that happen with cars on the road. Minor accidents [like this] take place almost daily,” Nikitin said.

“Major accidents or disasters, when both the ship is lost and the lives of those on board, happen rarely.”

Yet some navigational errors do lead to substantial damage to the sub or injuries suffered by crewmen – as was the case with HMS Trafalgar, a now decommissioned Trafalgar class submarine, which also ran aground near the Isle of Skye.

That November 2002 accident resulted in £5 million worth of damage to the HMS Trafalgar’s hull and injured three sailors. The vessel had been travelling 50 metres below the surface at more than 14 knots when a course change was ordered that took the sub onto the rocks at Fladda-chuain, a small but well-charted islet.

The officers responsible for navigation later pleaded guilty at court-martial to contributing to the accident and were in 2004 reprimanded by court for negligence.

In a similar accident of October 2003, USS Hartford (SSN-768), a United States Navy nuclear-powered Los Angeles-class submarine, ran into rocky shallows in the harbour of La Maddalena, Sardinia, while performing routine manoeuvres.

The accident caused approximately $9 million’s worth of damage to the submarine, which was out of service for seven months. Investigation showed the cause had been basic navigation errors combined with equipment failures.

In January 2005, another Los Angeles-class submarines ran aground south of the Pacific island of Guam, injuring several sailors of the 137-strong crew on board – including one critical injury, which resulted in a fatality the following day.

The nuclear reactor on that sub, the USS San Francisco, was not damaged in the incident. A US Navy investigation into the incident revealed in May 2005 that the USS San Francisco had “struck an undersea mountain about 360 miles southeast of its Guam homeport because its leaders and watch teams failed to develop and execute a safe voyage plan.”

Even though charts were available to the USS San Francisco’s navigation team that clearly displayed navigation hazard in the vicinity of the grounding, the team “failed to review those charts adequately and transfer pertinent data to the chart being used for navigation, as relevant directives and the ship’s own procedures required.”

In the Russian and, formerly, Soviet nuclear submarine fleet, accidents caused by navigational errors have been several times as frequent as those involving equipment failure, and radiation-related or nuclear accidents are even rarer, according to ERC Bellona’s Nikitin.

“Most often, accidents happen when the vessel is navigating through a narrow area or because of severe weather conditions. Running aground is not the worst navigation-related accident, especially if it happens in narrow waters, where the ship’s speed is at a minimum,” Nikitin said.

Maria Kaminskaya contributed to this report from St. Petersburg, Russia.