The international rescue mission which saved seven trapped Russian sailors was today hailed as an "excellent result" by British experts.
All the crew members were safe and well after their stricken mini-submarine finally resurfaced thanks in part to the help of a Royal Navy rescue vehicle.
The Scorpio 45 unmanned remote-controlled vehicle cut away undersea cables that had snarled the vessel, which was entangled 190 meters (625 feet) below the surface off the coast of the Kamchatka Peninsula.
Owned by the Ministry of Defence, the Scorpio 45, is about the size of a Smart car, with cameras, a robot arm and a cutting device.
A team of up to four operators led by Commander Ian Riches, head of the MoD's Submarine Escape and Rescue team, won the race against time as the crew's oxygen supplies rapidly diminished.
They were aided by their Russian colleagues and a small team of American divers who assisted the crew members with breathing apparatus.
The AS-28 mini-submarine resurfaced at around 2.25am BST today, some three days after being stranded.
Commander Jonty Powis, a Royal Navy specialist on submarine escape and rescue, said the operation, which lasted five-and-a-half hours, went "relatively smoothly". The Scorpio had to resurface midway through the mission for repair work to be carried out.
He said: "It was an excellent result in very trying circumstances.
"This was a fairly routine procedure, but the fact that we were dealing with people's lives created extra difficulties.
"We were conscious that the crew were running out of oxygen and that we could not afford any great delays in cutting them free."
Commander Powis said the operation was delayed for about an hour when a small repair to the cutting equipment was needed, but it did not effect the success of the rescue bid.
"We understand that the sailors are safe and well, and they had about 10 to 12 hours left in oxygen supply.
In contrast with the sinking of the Kursk nuclear submarine five years ago, in which all 118 on board died, Russia was quick to ask for international help to rescue the men.
Commander Powis said there was now far more international cooperation in the field, with the Russians sharing expertise with other nations.
He said: "The Russians have become completely involved and really very important participants in the world of submarine escape and rescue."
He praised the openness of the Russian authorities in allowing rescuers into what was once one of the most secretive parts of the Soviet Union.