PROVINCETOWN - I have mixed feelings as we head over to the truck parked at the corner of Standish and Commercial Streets in downtown Provincetown. Were about to pay for an hour-long narrated tour of the historic Provincetown dunes at Art's Dune Tours movable headquarters. On the one hand, I cant wait to see the dunes that most people never see, that have been protected by the Cape Cod National Seashore since it was established in 1961. On the other hand, it feels a little weird to be heading into the dunes in a heated white Suburban. (Its a chilly April day.) But curiosity wins out, and so we sign up and settle into the car, ready for a small adventure.

The spectacular seascape on Cape Cod is the result of ancient alchemy performed by nature: over many millennia, sand has been blown into dunes by the wind and then stabilized by beach grass. On its website, The Cape Cod National Seashore writes that the dunes were forested once, but land use practices of European settlers denuded the dunes and caused widespread migration of sand. Efforts were initiated in the early 1800s to stabilize the duneswith vegetation. But, says Dave Sprang, Seasonal Supervisor of the North District Interpretive Division, We dont try to control the environment, we try to protect and maintain it.

People have been viewing the dunes with Arts Dune Tours since 1946, when Art Costa founded the company. These days, Arts son Rob is behind the wheel, overseeing a fleet of six trucks that seat seven to nine people each. The first five minutes of our tour find us driving on regular old paved roads toward the sea. Next thing I know, though, I am heading off-road for the first time in my life, right onto the sand. It feels strangely thrilling to drive on the sand; even more so to drive over a hilly dune and see there, right in front of us, the ocean.

What is less thrilling, and even a little shocking, is to see that were not alone: were out here with at least a couple dozen jeeps, trucks and other 4-wheel drive cars. Theres practically a traffic jam out here on the protected National Seashore. Kenny, our guide, informs us that the Seashore sells more than three thousand permits a year allowing cars access to the beach. (They are sold out for the season.) Later this summer, he adds, there will be campers and RVs parked here, too.

So when I look to my right, Im imagining the virtual sea of vehicles that will be parked on the beach in a month or two. To my left, though, we are watching seals and whales frolic in the surf, as if ordered up by central casting. Meanwhile, the ever-courteous Kenny keeps giving friendly nods to all the other drivers who are sharing the beach with us on this cloudy, cool spring day.

Soon enough, I see that all the cars around us are pulling U-turns and heading back to the road. Was that the tour? I wonder, disappointment setting in, but then I see that off to the right is a sign: No entry except commercial dune tours. That would be us and only us, since Arts is the only dune tour company in town. (Others have come and gone, but none of them have survived, says Costa.) Now were getting somewhere -- or, even better, nowhere. We head up a hill and into the heart of the dunes, where suddenly were surrounded only by the seasons first tufts of beach grass, wild cranberry bogs, beach plums and sand. It is eerily beautiful, a gorgeous collage of browns and grays. (Kenny tells us that in a month or two, the land will be covered with pink and white beach roses.) Off in the distance, we can still see whales cresting and spouting in the sea.

Next we notice the small shacks built right into the dunes, which, Kenny tells us, have a long and illustrious history. These simple beach cabins have been said to inspire numerous artists and writers who have stayed in them during the past century, including Eugene ONeill and the poet Harry Kemp. I am told with assurance by various people that there are definitely 13, 14, 17 or 18 shacks still standing, but this isnt the only disagreement concerning the beloved buildings. The National Seashores Sprang says that ultimately, the Seashore will take possession of all but one of the shacks (which will remain under private ownership), but that the Seashore doesnt like to talk about the shacks fate since the future of the shacks is still up in the air. They probably also dont like to talk about the shacks because a number of families who had owned them for generations feel that the Seashore has strong-armed them out of their ancestral homes, and they arent happy about it.

All controversy aside, as I look out on these humble, historic structures set right in the middle of the dunes, I start dreaming of what it would be like to live out here for a week or two without any telephones, toilets, transportation -- or children, with only the stars and coyotes for company. My reveries are interrupted when a woman from the back seat of our car points to a sandy hill and laughs. This, she tells us, is where she came as a child to roll down the dunes. It sounds magical, but rolling down the dunes isnt allowed anymore. Kenny nods his head knowingly and says, It was just a lot of fun out here in them days. Sometimes, whats past is gone forever: no more kids rolling down the dunes, RVs on the beach. But the whales and seals are still here, and the shacks, I hope, will remain standing for years to come.

The neat thing is that people had gone out on the tour with my father when they were children, says Costa, and now theyre coming out with me and bringing their own children. As we head out of the dunes and back onto the highway, I am already planning a return trip to Arts Dune Tours. Next time, though, I think Ill bring my kids.