Five Britons detained in Russia as part of the so-called "Arctic 30" arrived back in the UK today where they were greeted by relieved friends and family.
The five were arrested amid claims of hooliganism following a protest about oil drilling, and held in jail for two months.
They have since been granted amnesty under a new Russian law.
Greenpeace member Anthony Perrett, 32, of Newport, South Wales, arrived in London with fellow activists Alexandra Harris and Phil Ball, crew member Iain Rogers and freelance videographer Kieron Bryan.
They left St Petersburg earlier today and arrived in Paris this afternoon before travelling to London's St Pancras station on Eurostar to be met by their families, a spokesman for Greenpeace said.
A sixth Briton, activist Frank Hewetson, has also been released and is travelling to another country.
Speaking at St Pancras, Mr Bryan's brother, Russell, said his return to the UK was "a massive relief".
"It's been a long few months for all the family. We're just so glad it's coming to an end," he said.
"It was very difficult when he was in prison. We couldn't really speak to him.
"We had one phone call and series of letters but the letters were way behind where we were.
"Even last week we were still thinking he could potentially face seven years in jail and face these ridiculous charges.
"It's a massive relief."
Mr Bryan said his brother Kieron, who lives in Peckham, south London, had decided to take a job in Afghanistan before his arrest in Russia.
"I'm sure Mum won't let him out of his room now," he added.
"I'm not going to stand here and pick his jobs.
"His job as a journalist inherently involves risks."
The Arctic 30 - 28 activists and two freelance journalists - were arrested after Russian authorities boarded their ship, the Arctic Sunrise, during an anti-drilling demonstration in September.
The group were detained for protesting against an Arctic offshore oil rig owned by the Russian company Gazprom.
They were initially charged with piracy, but the charge was later changed to hooliganism.
They had their passports returned to them after being freed on bail by courts in St Petersburg, but initially did not have visas to leave Russia.
Mr Perrett, who was the first to be released, spent Christmas Day in St Petersburg before being given the news that the Russian authorities had given him a visa and his passport.
He said earlier that the facility the activists were held in was like a concentration camp.
"We faced World War Two concentration camp conditions, at times," he told the BBC Radio 4 Today programme as he prepared to board the flight to the UK.
"We weren't treated like prisoners of war. It had very much the razor wire and the barbed wire and the reinforcing bar which made up the cages. It had the aesthetic of a concentration camp, not the conditions of."
Arriving at St Pancras, a tired-looking Mr Perrett told reporters: "It has been a strange few months, but it is over now and it is good to be back. We're very relieved to be home, it's good to be back and speaking English, which has been sorely missed."
Asked whether it had been worth it, he said: "W ell, look at the media that's here today. We're trying to spread the word to save the Arctic and I think we have done that job fairly well."
He added: "I'm looking forward to spending some time in the woods and getting at one with nature that we are trying to preserve."
Ms Harris said she thought the Russian government let the Arctic 30 go to avoid global criticism in the lead up to the 2014 Sochi Winter Olympics.
"I think it was the easy way out for Russia, to get rid of us before the Olympics began and before there's a big PR pressure from Greenpeace and the rest of the world," she said.
Ms Harris said the fact they were given an amnesty, despite doing nothing wrong, was "not ideal".
"But I'm not in a position to refuse it, I can't have seven years hanging over me," she said of the jail penalty she was likely facing.
But the activist said she would not rule out a similar protest again, despite slamming the appalling conditions she faced in custody.
"The conditions are really bad, it's cold, the food is unedible - it's not good," she said.
Ms Harris said it was knowing her 29 fellow activists were going through the same experience that helped her weather the ordeal.
She said the Arctic 30 had been treated better than Russian prisoners.
"B ecause the world's watching us and they're scared of what we're going to say now," she said.
"There was no physical violence towards me but it was torture - we spent two months in a Russian jail cell and 100 days detained for a crime we didn't commit.
"It was obscene, a complete overreaction on the part of Russia and we should never have been there."
Ms Harris said she was looking forward to spending time at home with her family in Devon and eating home cooked food.