This may not match your fairy-tale fantasy about royalty, but Prince Pieter-Christiaan of the Netherlands is a regular guy who answers his own phone.

Maybe that's the source of his popularity, which reigns highest among the Dutch. They like the fact that he champions humanitarian causes and chose love over a chance to be king.

Pieter-Christiaan is so laid-back, that when he joins 25,000 runners for Sunday's Honolulu Marathon, the prince would rather you ponder the charity he represents — the World Wildlife Fund — than his lineage.

In fact, if you didn't know his bib number — OK, it's 100 — you'd think he was just another runner dealing with sore knees, which will be the case this year.

But in pain, there is purity of purpose.

"I think a marathon is a very true way to bring attention to a charity," he said by telephone from his Amsterdam apartment. "If you train hard and push hard and try to run a marathon, wouldn't it be great if you could do something and raise attention for a good cause?"

With that in mind, Pieter-Christiaan, who also scuba dives, wants to call attention to overfishing in the world's oceans.

"The seas are becoming more empty," he said. "Not because of global warming but from fishing. We are helping species disappear. I think that is undeniable."

Consumers can change this, he said. They can take a stand against fishing practices, against miles and miles of nets that snare and kill a variety of creatures they are not intending to catch — dolphins, sharks, turtles, sea birds.

The 35-year-old prince has linked causes with his passion for long-distance running ever since he was 16.

"I use running as a tool," he said.

Once, the prince and several friends ran around Lake Geneva to raise money for a youth sports stadium. When he ran the Honolulu Marathon in 2002, he also represented the wildlife fund.

The prince is the nephew of Dutch Queen Beatrix. He was seventh in line to the throne but gave up his place in the line of succession when he decided not to ask parliament for the right to marry in 2005.

Pieter-Christiaan and his wife, Princess Anita, will arrive in Honolulu today. They'll be met at the airport by a local Dutch club organized by Nanja Linger, a 30-year-old Netherlands native who now lives in Waikiki.

The 40-member club is bursting with excitement at the chance to meet the man Linger called "the people's prince."

"He is very well-liked," she said. "He is down-to-earth. He is one of us. He is a good example, too. He is young, he just started a family, he is educated. He is great royalty to have."

The prince's lack of pretense means he blends in most of the time.

It happens so often that the Dutch consul in Hawai'i is trying to make the prince's Neighbor Island travel and rental car arrangements so that clerks will know who he is during his visit, said Pat Bigold, director for media relations for the Honolulu Marathon.

The consul has also invited two local royals to meet Pieter-Christiaan at a reception Thursday at the Hilton Hawaiian Village: Princess Dialta Alliata di Montereale and Princess Abigail Kawananakoa.

"The prince keeps such a low profile that no one knows he's royalty, and he occasionally encountered rudeness on his last visit," Bigold said.

Still, Pieter-Christiaan is not one to complain — he didn't in 2002, when he had to park his own car at a Honolulu Marathon reception at the Oahu Country Club.

"He was just a regular guy," Bigold said. "He didn't care."

His good nature that year also extended to the marathon. The prince — the only royal to ever enter the race — said he helped pace a stranger through a difficult portion of the course, even though he was also suffering from the flu.

To deal with a tropical climate quite unlike Amsterdam in December, the prince has adopted some unusual training methods.

"I train in double gear," Pieter-Christiaan said. "I keep myself extremely hot. I look like an eskimo running over our pathways here, trying to simulate the heat."

This time around, his knees may bother him more than the weather.

"I don't want to say I am fragile at this age, but I do have more problems than I want," he said. "This one might hurt."

Given that a marathon covers 26.2 miles, most runners will probably be feeling the same pain. The people's prince will fit right in.

Reach Mike Gordon at mgordon@honoluluadvertiser.com.