Whidbey Islanders will see a man who has been called “the ultimate running specimen” legging his way down the island Sunday morning.

Dean Karnazes, an ultra-endurance runner and author of the best-seller, “Ultramarathon Man: Confessions of an All-Night Runner,” will be among an estimated 2,300 runners and walkers participating in the fifth annual Whidbey Island Marathon and Half Marathon.

Runner’s World magazine gave Karnazes the moniker of the “ultimate running specimen.” He was lured to the island by this year’s race sponsor, Nature’s Path Foods.

“The goal is to make the Whidbey Island Marathon and Half Marathon a world-class competition,” said Davie Neuman, Nature Path’s executive vice president of global sales and marketing, in a news release.

Karnazes’ Web site describes him as “an internationally recognized endurance athlete who has pushed his body and mind to inconceivable limits.”

Men’s Fitness magazine in its March 2006 issue describes Karnazes as perhaps “the fittest man in the world.”

Islanders will be challenged to keep up with Karnazes in the 26.2 mile race from just north of the Deception Pass Bridge to Coupeville Town Park.

Karnazes’ lengthy list of feats says he has run 350 continuous miles, run across Death Valley in 126 degree heat, run a marathon to the South Pole in minus 40 degree cold, and he’s run a 200-mile relay race solo.

He’s a ten-time Western States Endurance Run Silver Buckle winner, and won the 2004 Badwater Ultramarathon, billed as “the world’s toughest foot race.”

Karnazes has appeared on numerous national TV and radio shows, and his book won the “Best of Amazon 2005” award in two categories, number five overall in sports and number two overall in health/mind/body.

Despite his accomplishments, Karnazes in no sure bet to win the Whidbey Island Marathon, which has attracted some of the best runners in 25 states as well as Canada.

Hundreds of runners and walkers will be on the roads of North and Central Whidbey Sunday morning, April 2, participating in the fifth annual Whidbey Island Marathon and Half Marathon.

Approximately 500 marathon runners will join Karnazes in the start just north of the Deception Pass Bridge at 8 a.m.

At 8:30 a.m., some 1,800 half-marathon participants will depart from Olympic View Elementary School in Oak Harbor.

The runners will make their way to the finish line at Coupeville’s Town Park mostly by back roads, including Monkey Hill, Henni, Jones, Taylor, Crescent Harbor, Regatta, Scenic Heights and Madrona.

Flaggers will be out in force to direct traffic, and other volunteers will be manning water stations and otherwise helping the runners on their long trek.

Registration for the event takes place today, April 1, at the Marathon Expo from 11 a.m. to 4 p.m. at Oak Harbor High School.