If it walks like a duck, and quacks like a duck, it must be a tank.

Such confused being will likely be invading the Square and the Boston area soon, if entrepreneur Andy Wilson and partner Manny Rogers succeed in a new business venture intended to use World War II-era amphibious vehicles as Boston-area tourist transport.

But the pioneers must first overcome opposition from Cambridge neighborhood organizations, which argue that the tour vehicles would increase traffic in already-congested streets and cast an unwanted militaristic images on the city.

"Ducks"--a simplification of the military acronym DUWK--are military vehicles that wee built from 1943 to 1945. For the past 30 years, they have been used in locations across the country as tourist vehicles.

The ducks "are basically buses that float," Wilson said.

Wilson will paint the 8-foot by 32-foot ducks in camouflage colors in order to "restore them in a military theme," which he believes will be in keeping with Boston's past as "the birthplace of freedom."

World War II was the biggest event that stabilized freedom across the world," Wilson said. "I believe that the people of Boston will react very positively to this."

Wilson, the president of Seaweed Inc., the holding company of Boston Duck Tours, L.P., resigned as vice president at The Boston Co. last year to take a bus tour across America.

It was in Memphis, Tenn., that he first saw the amphibious ducks being used as tourist vehicles. After seeing them again in Wisconsin and Missouri, he decided to try his hand in bringing them to Boston.

He joined forces with Rogers, World War II history buff and president of Rogers Funeral Home, and together they formed plans for the operation of a duck tour around the sights of Boston and Cambridge.

The two hope to begin the operation of four ducks by May 1, 1994. The 90-minute tours would take passengers through Boston to Cambridge-via the Charles.

Boston Duck Tours plans to take full advantage of the ducks' water-travel capacities by integrating tours of the river into its three possible routes for city tours.

Wilson added that he has already takes a group of 30 Japanese business executives on a duck tour, and they "loved it."

The Harvard Square Defense Found, however, does not favor Wilson's idea quite as much as the out-of-town visitors. The neighborhood organization is concerned that this "make way for ducks" scenario will increase traffic in an already crowded area.

"In cities as crowded as Boston and Cambridge, [the duck tours] will only be detrimental," said Howard D. Medwed, vice president of the Defense Fund. " Tourists should use existing public transportation."

Gladys P. Gifford, the Defense Fund'spresident, said the military theme would send thewrong message to the large numbers of foreignvisitors to Boston and Cambridge.

"In Harvard Square we want to encourage tourismappropriate in character that tells a tale aboutCambridge," she said. "The history of Boston andCambridge is not military. To emphasize themilitary is to do a disservice to them."

John R. Pitkin, president of the Mid-CambridgeNeighborhood Association, concurred. "It's goingto be an assault of these kinds of vehicles onCambridge."

But Wilson said that his duck tours will notdiffer markedly from the already existing trolleytours that operate in Boston and Cambridge.

"I feel that [the Defense Fund] is selectivelycutting me out in a very undemocratic way," Wilsonsaid. "I don't understand why motorcoaches twiceas big can go through [Cambridge], but I can't."

Wilson said that if necessary, he may removeCambridge from the current plans for tour routes.

While Boston Duck Tours has already receivedapproval from the Cambridge License Commission,the new firm has been denied the use of MemorialDrive and the banks of the Charles by theMetropolitan District Commission, which controlsall park lands.

The company is now awaiting decisions from theCambridge City Council and Department of PublicUtilities, which has the ability to override theother agencies' decisions