BAR HARBOR – Retail giant L.L. Bean will donate $1 million to expand the Island Explorer bus service on Mount Desert Island.

Bean will donate the money to Friends of Acadia, a nonprofit membership organization, which will award annual grants to the Island Explorer to meet the growing demands for bus service in and around Acadia National Park, officials announced Tuesday.

“L.L. Bean’s inspiring gift sets a significant conservation precedent as the first corporate contribution to nonprofit public transportation in the country’s 385-unit National Park System,” Ken Olson, president of Friends of Acadia, said in a prepared statement.

Among other projects, the money will be used to expand the bus service into the off-season, beginning in the fall of 2003, and to buy new “desperately needed” buses, according to Ed DeWitt, manger of Downeast Transportation of Ellsworth, the owner of the nonprofit Island Explorer bus service.

Chris McCormick, Bean chief executive officer, said the Freeport-based retailer wanted to help Acadia at a time when the park faces increased use and underfunding by the federal government. The Island Explorer not only helps keep down traffic at the park, it cuts pollution and helps protect the natural resources of the nation’s second-most-visited national park.

“The impacts of pollution on the park are of great concern to a company whose foundation is to promote recreation and sound stewardship of our natural resources,” McCormick said in a statement.

Bean company leaders will present the gift at 2 p.m. Friday on the Village Green in downtown Bar Harbor. They will be joined by members of Friends of Acadia, the National Park Foundation, and Acadia National Park.

When the Island Explorer bus service was created in 1999, organizers projected 1,000 riders a day. By last summer, more than 5,000 people used the service on its busiest day, a 75 percent increase over its inaugural season.

All told, the bus service carried 240,000 passengers last year, removing 80,000 vehicles from park roads.

The bus service will cost about $570,000 to operate this year, with Acadia paying $306,000 from gate fees and the U.S. Department of Transportation providing $150,000.

Although the rides are free, passengers voluntarily contribute about $10,000 a year in fees. The four island towns also contribute money to the service; they will pay $59,000 this year, or about 10 percent of the overall cost.

“The L.L. Bean donation is a magnificent expression of corporate stewardship,” David Rockefeller Jr., a Mount Desert Island resident and member of Friends of Acadia, said Tuesday in a prepared statement.

Rockefeller, whose grandfather, John D. Rockefeller Jr., helped create and expand Acadia, added, “I hope other businesses will emulate it throughout the national park system.”

The Island Explorer project was created as an outgrowth of the MDI Tomorrow effort of 1991, which charted a path for the future for the island, park and communities. It has been supported by numerous groups and agencies, including the federal and state transportation departments, MDI businesses, Friends of Acadia and the park itself.

The bus service launches its new season on Sunday and will run through Labor Day.