When you drive out of Winter Harbor onto the Schoodic Peninsula and see a sign welcoming you to Acadia National Park, you may think you are entering the Schoodic area of the park. Think again. You have another two miles to go. The park owns only the relatively small southern tip of the peninsula.

First, you pass through a 3,200-acre tract that is privately owned. And what the owners may decide to do with their vast property is such a worry for the park’s superintendent, Sheridan Steele, that he recently described the situation as “the biggest single threat to Acadia.”

Owners Bruno and Victor Modena, who live in Milan, Italy, are said to visit Down East Maine occasionally but are thought not to have ventured onto their Schoodic property. The only known use they have made of it thus far was some timber harvesting in 1996. The biggest fear among park supporters is that the owners might decide to subdivide and open the way for a community of luxury summer houses next to the park.

The current fears have ridden on a 2004 inquiry by a Greenwich, Conn., consultant, Everett Shaw, representing the Modenas. He wanted to discuss a range of options for development with the park, as an abutter. That call led to a single meeting of Mr. Shaw with officials of the park, Friends of Acadia and the Maine Coast Heritage Trust. The officials still have no idea of the Modenas’ intentions, and Mr. Shaw has often been hard to reach. He did not respond to a telephoned request for comment.

Similarly elusive have been the Winter Harbor Holding Co., which nominally holds the title, and Siren Property Management, a New York City firm said to manage the property.

No wonder that the park superintendent warns of “incompatible development” and “negative impacts.” Or that other officials have found the matter “quite frustrating, to say the least.”

Still, the timber cutting 10 years ago went well from the park’s viewpoint. There was no clear-cutting, and the selective harvesting was out of sight from the park. But since then, not much has happened.

What would suit the park? First of all, the park has no hope or even possibility of acquiring the Modena tract. A 1986 law fixed the park’s present boundaries. The park planner, John Kelly, would like to see an easement negotiated with the owners by either the park or a third party such as the Maine Coast Heritage Trust, to protect the property for the indefinite future.

Another possibility would be to work closely with the owners on a development plan that would guarantee wildlife movement, protect wetlands, avoid visual impact on the park and favor unpaved roads rather than hard surfaces that would interfere with runoff.

A last resort would be relying on land-use ordinances and requirements of the State Planning Office.

In any event, the Schoodic Peninsula is a jewel that must be cherished and protected.