Dan McDermott once leapt from a plane and parachuted onto the grounds of the Darlington nuclear power plant.

The 1979 publicity stunt — or "mind bomb," as Greenpeace would call it — on the shoreline of Lake Ontario was just one of many bold moves McDermott would make in the name of defending the environment during his life, which ended at age 69 earlier this week.

CBC Archives | Watch Dan McDermott's nuclear protest

John Bennett, who helped McDermott launch Greenpeace Toronto, said his friend was always thinking of new ways to protect nature, from scaling smokestacks to protest acid rain or working behind the scenes to pressure Ontario's government into eliminating coal-fired power plants.

Not every campaign worked, Bennett said, but it's clear McDermott made the air Ontarians breathe better.

The Globe and Mail ran this image of Dan McDermott's Darlington stunt. (Globe and Mail/CBC Archives)

Joyce McLean, who also worked at Greenpeace in the 1980s, said McDermott's devotion and courage inspired everyone around him.

"He was an extremely principled person," McLean told CBC Toronto. "He dedicated his entire career to this — and it's not a well-paid job.

"He had a heart as big as you can imagine."

Both Bennett and McLean said they believe McDermott's love for nature drove his activism. He could often be found hiking in the Don Valley or Rouge Park with his late wife, Helen Rykens, McLean said.

Activist made his points clear

Thomas Hart, a Toronto philosophy professor, said that despite the wild stunts, McDermott was often an unassuming presence who would sit quietly and let everyone in the room speak before him. But he was very well-spoken, Hart said, noting he and McDermott had worked together to deliver a major lecture about Bob Hunter, one of Greenpeace's co-founders.

"Now once he opened his mouth, you were going to know exactly what he thought," Hart said of his friend. "He didn't sugar-coat anything."

'No nukes!' Dan McDermott and other Greenpeace Toronto protesters chant outside the Darlington nuclear plant during a 1977 demonstration captured by CBC News cameras. (CBC)

It helped, Hart said, that on most environmental issues McDermott was practically unassailable.

After his time at Greenpeace, McDermott went on to work at Earthroots and the Sierra Club Canada Foundation.

In his final Sierra Club news release, McDermott encouraged Ontarians to write to Premier Kathleen Wynne and tell her to block policies that could see Toronto's greenbelt "turned into a Swiss cheese belt."

A Toronto island goodbye

The Toronto Star featured this image of Dan McDermott in 1980, dubbing him 'a honcho in the Non-Nuclear Network.' (Toronto Star/CBC Archives)

Shortly after that, the club organized a trip to Ward's Island to celebrate McDermott's retirement.

Gretchen Fitzgerald, who was there that day, broke down in tears as she remembered McDermott's final speech to those in attendance. With characteristic wit — he was always fond of puns, several friends recalled — McDermott spoke about nature's importance and the need to protect it.

Fitzgerald said she was always amazed by McDermott's ability to approach complex environmental issues without wearing rose-coloured glasses or feeling completely deflated. And he could always help others do the same, she said.

After the event, she wrote a touching tribute to her colleague and friend on the Sierra Club's website.

"Although cynical, even curmudgeonly, about the political motivation behind many of our environmental problems, it's clear that Dan is at heart an optimist," she wrote. "Otherwise how could he have fought so hard for so long, and inspired others to use their unique talents to do the same?"