Three UK explorers who endured frostbite and food shortages had mixed feelings at the end of their pioneering Arctic research expedition.
On Wednesday, two aircraft landed on the floating Arctic ice to collect Pen Hadow, Ann Daniels and Martin Hartley.
They have been measuring the thickness of the sea ice as they trekked across the Arctic.
Expedition leader Pen Hadow told the BBC that the experience had been "very tough".
The explorers hope their data will help scientists better understand the impacts of global warming in the region.
Last night I joined the flight that picked up the Catlin Arctic Survey team from the frozen Arctic Ocean.
They were just 500km (300 miles) short of their original destination, the North Pole.
As he prepared to leave the ice, expedition leader Pen Hadow told me he felt "relief".
He said: "We've learned a lot about what's possible and what's not possible."
Most frustrating for Mr Hadow and his companions, Ann Daniels and Martin Hartley, was the failure of a new radar device to measure the sea ice, and a hi-tech communications system to transmit the data.
Both had been successfully tested in trials, but were dogged by breakdowns from the earliest days of the expedition.
The expedition was brought to an end 10 days early amid concerns about the summer break-up of the ice - several other research teams on the sea ice had already been withdrawn.
On our approach to their camp, the area was scarred by massive cracks and breaks exposing dark water.
During the 10 weeks of the Catlin Arctic Survey, the explorers resorted to drilling by hand to make thousands of measurements, discovering that this region of the sea ice is more vulnerable to melting than expected.
The expedition was initially blighted by unexpectedly cold weather with the wind chill lowering the temperature to about -70C (-90F).
At the time, Mr Hadow came up with a memorable description of their plight: that they were "battered by the wind, bitten by frost, bruised by falls on the ice - and likely to be butchered by the chill."
Ann Daniels, the navigator, medic and cook, told me how it took "true grit" to keep going when temperatures inside the tent were in the "minus thirties".
She told BBC News: "I can remember just sitting there feeling my fingers and my feet getting frost damage and sobbing because I knew that I was really being damaged.
"One of my releases was to sob quietly. The boys weren't there for that to make them feel bad. I would just keep going knowing that, in the end, the beauty would come out and the sun would be shining."
Photographer Martin Hartley suffered frostbite in the first few days.The pain was so bad he considered being airlifted off the ice.
He said: "It was like putting a red-hot knitting needle into my toe and then putting it into my boot with the knitting needle still attached to the toe."
Mr Hartley added: "But the motivation to be here was so strong. I'd much rather be here in pain than at home recovering."
The weather delayed two of the re-supply flights - one was 11-days late forcing the team to eke out their remaining food.
At one stage, Ann Daniels allocated each of them just 90g (3oz) of food a day, and she described how the normally jovial mood in the tent subsided into one of lethargy.
Suffering for science
Despite the hardship, the team managed to gather 16,000 measurements along the line of their trek, finding an average thickness of the ice of 1.77m (5.81ft).
Asked whether the expedition was worth it, Pen Hadow said: "We feel we've given data that's sufficiently voluminous, accurate and comprehensive, and over a period of time and a long distance. That's going to be useful."
The team is now in the remote Inuit settlement of Resolute Bay - the first chance for a hot shower and a night in a bed since the end of February.