JULY 10, 1985. Marsden Wharf, Auckland, New Zealand. Peter Willcox was in a deep sleep until the sound of the first bomb woke him and sent a large tremor throughout his entire ship.

He got up, and realised that the vessel had fallen unusually silent. Unable to find his glasses or even his clothes in the darkness and confusion, he stumbled out of the captain's cabin wearing only a towel. Some crew members were staring down into the engine room. Water had almost filled it, and was even now rising close to the main desk where they were standing. Then, less than two minutes after the first explosion, there came the sound of a second one.

This was the fate of the Rainbow Warrior, the Greenpeace ship that was deliberately sunk by French intelligence agents as it sought to disrupt French nuclear testing in the Pacific. A Greenpeace photographer, Fernando Pereira, was killed in the process.

Nothing, however, could ever deter Peter Willcox from his chosen career. Today, 32 years after the attack on Rainbow Warrior, which he had captained, he remains an indomitable figure in the never-ending battle to save the planet. In September 2013 he was one of the "Arctic 30" – a group of 28 Greenpeace personnel and two freelance photo/video journalists who were detained on board the Arctic Sunrise by armed Russian coastguards as they tried to unfurl a banner denouncing Russia’s attempts to drill for oil in the Arctic, on the Gazprom oil rig, Prirazlomnay, in the Pechora Sea. The arrests sparked worldwide protests, and letters of condemnation from world leaders. Even the Pope got involved.

In a way, Willcox, a 63-year-old American, was born to this sort of non-violent direct action. When he was three months old he was adopted by what he describes in his newly-published memoirs as a "left-wing, antinuclear, antiwar, socially progressive, hardcore-offshore sailing family". His adoptive father's father, Henry, a prominent public-housing builder in the New York City area, had been involved in left-wing groups; at one point, Henry and his wife Anita fell foul of Senator Joseph McCarthy and had to testify before the notorious House Un-American Activities Committee (HUAC).

Willcox's adoptive father, Roger, was a champion sailor; his mother, Elsie, a union organiser then a science teacher. And Willcox himself was just 12 when in March 1965 he and his father joined in the culmination of Martin Luther King's civil rights march from Selma, Alabama, to the state capital of Montgomery. Civil rights, he says in his book, "was a very big deal in m family".

Willcox was an experienced sailor by the time he became captain on the Clearwater, a sloop established by Pete and Toshi Seeger to carry out environmental awareness work on New York's Hudson River. He first encountered Greenpeace at a 1977 anti-nuke concert in New Hampshire. In 1981, lured by a "sailors wanted" ad by Greenpeace, and liking what he knew of the environmental activist group, signed up, becoming a deckhand on the Rainbow Warrior.

Today, he has some 400,000 sailing miles and four decades of environmental activism to his name. He has led Greenpeace crews into actions all over the world: Peru, the Soviet Union, the Marshall islands in the Pacific, the Amazon, Turkey and Sweden, on actions targeting everything from whaling to nuclear weapons testing. Despite the bombing of the Rainbow Warrior, despite his more recent confinement in Murmansk and Saint Petersburg's Kresty prison, he remains utterly wedded to the cause.

"I never really thought that they would lock us away for 10 to 15 years," he recalls of the sentence that the Arctic 30 would have suffered had they been convicted of piracy. "The hard thing about it was the uncertainty. Everybody around us – all the guards, the prosecutors and the investigators – were quite certain we would get 10-15 years, because really that's the way the Russian judicial system works. Once you're put in detention you are found guilty at trial, and they were giving us Russian dictionaries. But I didn't think so.

"For me, even though I had never been in jail for more than an overnight, once before, it felt familiar: we had gotten ourselves into a predicament and now we had to work our way out of it. But, as always, one of the things that helps us is that Greenpeace is 100 per cent non-violent, so we didn't qualify as pirates, and even [President] Putin said that, the day after we were brought to shore. He said we weren't pirates, but bad people, yet the only charge they could lay on us for arresting us on the high seas was piracy, so it was going to be very hard to make that stick.

"But I think somebody at the top of the Russian system decided we had become a big enough nuisance that they wanted to just chill us out and let us smell the toilets for a couple of months, and that's what they did."

The Arctic 30 spent two months in prison before being freed under a Putin amnesty prior to the Sochi Winter Olympics.

Willcox's detention separated him from his wife, Maggy, back home in Maine. They'd first met on the Clearwater in the mid-1970s, but had gone on to marry other people. Both later became single: the couple had met again in 2011, marrying in 2013, not long before Willcox set sail for the Pechora Sea.

Greenpeace has not staged any direct actions on that gas-rig since. "We have not been back to Russia to that Gazprom facility. At this point I'm not sure if I would go again. I mean, if I ended up in a Russian jail again, my friends and family would just think I was stupid ... I don't know of any plans to go back there, I haven't heard of any, and I think that, Russia being what it is today, it's really silly to pull on their tail that hard."

Willcox says Greenpeace's direct actions have a dual purpose. "We do it to educate the public: we want to make people aware that something is going on, we want to get an issue into the public discourse. That's the biggest reason for doing the actions. If they're good enough, they'll be covered by the press, and the word will go around.

"But the actions [are also] extremely energising for us. Everybody in society is looking for a way to contribute to society, and we all find different ways of doing it. But when we step outside of our sphere of immediate concerns and do something, not necessarily for money or for anything else, we become happier people. That's very important. We shouldn't forget that.

"In Greenpeace, if you want to see an unhappy crew, look at a crew that hasn't done an action for three or four months and has just been doing open days."

But Greenpeace is about more than just direct action, he says. It carries out lobbying; it has representatives in Brussels and all over the world. We have scientists, we have laboratories."

The scale of the organisation's reach was highlighted by a fisheries campaign conducted in the southwestern Pacific a year and a quarter ago. "We only found one boat that was obviously breaking the law," he recalls, "but because we had six or eight campaigners on the ship, because we had campaigners in Auckland and Taiwan and Brussels, we were able to get Taiwan issued with a yellow card so that they were told that unless they could demonstrate improved fishing practices, they would be banned from importing fish to the EC within six months.

"That was a huge thing that I know we could not have pulled off 25 years ago, and I doubt whether any other group could have, because it was a combination of efforts."

In his book Willcox concedes that he would have liked to have seen more of Anita and Natasha, his daughters from his first marriage, throughout his long Greenpeace career, but, as he says: "I've been away working to defend the environment that they'll be living in after I'm gone, so I'm good with that."

But Greenpeace's work is never done, and global warming remains the biggest environmental crisis. "The damages it has created already are becoming more obvious and easier to see, and have more and more people paying attention to what we are saying about it," Willcox says. "There were days last year when Scotland and Denmark produced all their energy through wind-power, and that's a hugely important thing, because what we know about global warming is that we have to leave fossil fuels in the ground and not burn them.

"The US elections were a huge step backwards. To have a president who denies climate change ... It's high-school science, it's not difficult to understand. But to deny it is a huge step backwards at a time when we cannot afford it.

"We have to work as hard as we possibly can to mitigate the damage we're doing. What we do this year is one-quarter of what we'll have to do in five years. So it really concerns me now that we're facing this in the United States."

Our conversation took place at the same time Rex Tillerson, former chief executive of Exxon Mobil, was being put forward as Donald Trump’s Secretary of State. “Remember, Exxon has known about climate change for over 40 years and, rather than deal with it responsibly, they spent billions of dollars burying it and refuting it,” alleges Willcox, alleges Willcox, echoing a point that Greenpeace has long argued, but which Exxon Mobil rejects as “discredited claims by anti-oil and gas activists”, adding that its scientists have been studying climate change for more than 30 years, much of it in conjunction with government bodies and research universities, and that it acknowledges the “risk of climate change is clear and the risk warrants action”.

"If the United States tries to pull out of [the] Paris [climate change agreement] it will find itself branded as a rogue nation," adds Willcox. Reports last Monday quoted a former Trump aide, Myron Ebell, as saying that Trump would “definitely” quit the Paris agreement.

The basic facts of climate change are, dismayingly, ignored or treated with contempt by some corporate interests. Money and greed are the reasons why, Willcox believes.

"Greed is a very strong human emotion and I'm not sure how you combat it. But as far as I'm concerned, oil company executives are selling the futures of their children and grandchildren for money. To me, that's the height of irresponsibility and greed. I think they're acting irrationally.

"How you fight greed is a bit of a mystery to me. We're pointing out the damages that climate change is creating, the loss of the Pacific islands, the loss of the habitat in the Arctic. All it's going to take is one good typhoon ...

"Are you aware, for instance, that India has built a thousand-mile-long fence between it and Bangladesh? So that when Bangladesh floods, the people that need to escape to higher ground won't be able to. That's just so destructive in my mind it's just hard to comprehend, but I've seen pictures of it.

"When I started this job in 1973," he adds, "I never would have imagined that we'd be in the position where we are now, where I'm realistically scared for the future of my children. I'm reaching retirement age, but I'm not going to [retire]. I'm going to keep going, because it's so critical. We're at such a desperate point, a fine line, that we have to do everything we can to mitigate the damages we're creating. The time is critical.

"The biggest thing we can do is work together. When we do that we are much more effective than doing it as individuals. We can pressure our politicians, do things in our communities, buy cars that aren't so polluting. The list goes on, but when you work as a group it's much more satisfying and you can get much more done."

Greenpeace Captain: Bizarre Wanderings On The Rainbow Warrior is published by Sandstone Press, £9.99 www.greenpeace.org.uk