A 500-mile, 40-day journey across northern Spain

Five hundred miles on foot over 40 days.

Those stark figures only begin to sum up two Shelter Islanders’ walk across northern Spain from the end of March into May. It was a trek decades in the making to participate in the ancient pilgrimage of Camino de Santiago.

Translated as “the Way of St. James,” or, by those who make the long hike, simply as “the Camino,” P.A.T. Hunt, 64, and Harriet O’Halloran, 72, completed the journey they both had dreamed about for years.

Ms. Hunt first heard about the Camino about 20 years ago. She described the idea that wouldn’t leave her as “a longing.”

She compared it to a feeling she had as a young woman, not long out of high school in New England. “I had a longing to go to California,” she said. And with a couple of friends in a Volkswagen bus, she took the hippie trail to the Golden State where she lived for about a year.

“I thought about that on the Camino,” she said. “I never regretted that initial response to go. There was uncertainty, but part of me wanted to go into the uncertainty.”

For Ms. O’Halloran, the seduction of the Camino began almost 50 years ago when she was a student at Trinity College, Dublin, and made several trips to Spain. “I talked about going for years,” she said.

The Camino is one of the oldest pilgrimages in history, predating Christianity, with pagan Celts dedicating time to make the journey. It became one of the three important journeys Christians made in medieval times, the others being to Rome and Jerusalem.

In the Middle Ages, many European pilgrims — and some still today — began their spiritual voyage by just walking out their doors and heading for Santiago de Compostela, a town near the Atlantic in the northwestern tip of Spain in the province of Galicia.