Dahinden was born in Switzerland and moved to Canada in October 1953, where he would live for the rest of his life.
He became interested in the Bigfoot phenomenon shortly after arriving in Canada, and during the next few decades he conducted many field investigations and interviews throughout the Pacific Northwest.
Dahinden was a major advocate for the controversial Patterson–Gimlin film, which was shot in 1967 and supposedly provides photographic evidence of Bigfoot.
David Suchet's French Canadian Bigfoot-hunting character in the 1987 film Harry and the Hendersons is based on Dahinden.
In an obituary in the National Post, his friend Christopher Murphy remembered a remark of Dahinden's: "One day he said to me: 'You know, I've spent over 40 years – and I didn't find it.