CRANBERRY ISLES, Maine — The exercise itself suggests a modicum of tedium — running from one end of a two-mile road to the other again and again.

But it’s the extras that have made The Great Cranberry Island 50K Ultra Marathon unique to some of the country’s longest of long-distance runners.

There’s that initial inviting notion of spending time on an idyllic Maine island — Great Cranberry is located some 30 minutes by ferry southeast of Mount Desert Island.

There are the unique vistas that can only be seen from beyond the mainland, like the back side of MDI’s Cadillac Mountain.

There’s also a big postrace lobster bake where runners — most of whom camp out at the island’s community field the night after the event — meet, mingle and celebrate, and the annual Ladies Aid Society breakfast that is served the following morning.

Finally, perhaps, there’s something just plain ironic about the idea of running an ultramarathon — in this case 31 miles — on a land mass just two miles long and a mile wide.

This year’s seventh — and final — edition of the Great Cranberry Island 50K Ultra Marathon, scheduled for 11:30 a.m. Saturday, offers participants something even beyond its typical mix of athleticism and ambiance: a chance to be crowned a national champion.

The GCI 50K has been designated by the Road Runners Club of America as its 2013 national ultramarathon championship, which will lure a field of 192 runners from 30 states and several countries to the starting line.

“Perhaps what made us stick out to the RRCA was the Maine island picture, and the slightly cooler temperatures we have compared to most in the U.S. at this time of year,” said race co-director Gary Allen, a 12th-generation native of the island who grew up training for his own long-distance career by running back and forth along its only paved road.

Location and reputation, indeed, were two key factors in the selection of the race as the national championship, according to Jean Knaack, executive director of the RRCA, based in Arlington, Va.

“The RRCA board conducts a competitive bidding process each year and the ultra distance was a very competitive category, with several races bidding for the championship,” Knaack said. “The Great Cranberry Island Ultramarathon has a great reputation and the event takes place in a popular vacation area, which is a good fit for an RRCA championship event.”

The national championship designation has increased this year’s field from the 13 runners who participated in the inaugural event in 2007 and the approximately 80 who ran a year ago, when it was selected to serve as the RRCA’s Eastern regional championship event.

The runners, family members and support teams will add an estimated 500 people to the island’s population for a day or longer. Great Cranberry Island typically is home to 36 full-time residents and some 200 people during the summer months.

“Logistically, having a race on a Maine island presents some challenges, compounded by the fact that everything is more labor-intensive,” said Allen. “So it’s been all hands on deck, and the islanders have really embraced this.”

The start-finish line is situated about a half-mile from the town dock, with each runner going back and forth — two miles up and two miles back — along the rolling route approximately seven times to complete the distance.

“It might seem a lot like pulling teeth,” said Allen, “but a lot of people who run it said they like it this way, that the many repetitions out and back are better because there are no surprises for them.

“The spectators really get to see the race unfold, they can watch the lead changes and different strategies, and with the turnarounds at each end of the island all the competitors feel like they’re much more a part of the race because they’re seeing each other all the time. They feel like they know each other by the end of the race.”

David Goodrich of Houlton, a 56-year-old clinical social worker at the Aroostook Mental Health Center, is one of just two runners — along with Cliff Rodgers of Ellsworth — who will have competed in all seven GCI ultramarathons when he crosses the finish line Saturday.

And while he doesn’t expect to be among the leaders — Goodrich hopes to finish in about double the winner’s time, which should be near 3 hours — his specific time is well down the list of reasons he has kept coming back.

“For one, it was the first ultramarathon I ever did seven years ago, and with everything about it, it has the allure to keep bringing me back,” said Goodrich, who originally arrived on race day but for the last two years has come a week in advance with his family.

“A lot of it is because it’s on the coast of the Maine. There’s such an enduring quality about the coast and the people who live here and their persistence in being able to deal with a lot. There’s something about that that’s wonderful.

“In 2007 when I first came here I remembered how the people here really opened up their island, their haven, their place of life to us and really were welcoming. Now year after year I keep making friends and they keep having us back.”

One way to make friends is by passing them during the race, often while running in opposite directions.

Allen and co-director Mary Ropp, also founders of the MDI Marathon held each October, make sure each runner’s first name is printed above their respective bib number.

“You feel safe because you’re always going past the start-finish line, and if I ever needed anything, there it was,” Goodrich said. “And to keep seeing people running back and forth and offering encouragement to each other every mile or two is special. You get to meet people from around the United States in a unique way. It’s like an extended family.”

And while the race serves as a reunion of sorts to some, it is also a competition. Allen did not specify any clear favorites, but did say the women’s field in particular should be fairly deep, including 2010 GCI 50K women’s champion Amanda Labelle of Rockland and Sarah Mulcahy of Baring.

“There will be some very good runners out here,” said Allen. “The women’s field will be one of the strongest assembled in Maine for a marathon. There’s more than a half-dozen who have had some very strong finishes, both from Maine and beyond.”

The winners of Saturday’s race not only will be national champions, but also the event’s final champions, as Allen and Ropp have decided not to hold an eighth GCI 50K next year.

“It’s hard to explain to people why we’re ending it,” said Allen, “but we figured that rather than letting it get old and perhaps stale, this was a chance to end on a high note. We were named Runners World ‘Best Race Ever’ in 2011 and now we’re holding a national championship, we’ve kind of reached the top of the mountain.

“So why not let history remember this race as the special event it is?”

Ernie Clark

Ernie Clark is a veteran sportswriter who has worked with the Bangor Daily News for more than a decade. A four-time Maine Sportswriter of the Year as selected by the National Sportscasters and Sportswriters...