Is Cape Cod a peninsula or an island?

It’s one of those seemingly harmless questions that could probably lead to some sharp exchanges around the dartboard at the local pub on a Saturday night.

Dude, if you can row a boat around it, it’s an island …

That’s crazy, islands have to be born that way. Canals don’t count …

Points taken.

Some Cape residents roll their eyes at the notion of this sandy something-or-other extending 65 miles into the Atlantic being referred to as an island. Others talk about crossing the bridge "to the mainland.”

At least 108 Cape Cod Times readers wonder which is correct, and whether the state has an official designation for the Cape, based on Round 6 online voting in the Curious Cape Cod series.

A half-dozen state agencies tossed the question around like a hot potato; no one would go on the record. One kind and intrepid soul, on condition of anonymity, said he thought the state would consider it to be neither an island nor a peninsula — that it is simply a cape.

I next turned to the scientific community in our own backyard for answers.

Bull's-eye!

Andrew Ashton, an associate scientist at Woods Hole Oceanographic Institution whose specialty is coastal geomorphology, said the answer involves some technicalities.

“I would have to agree that after construction of the canal, water now surrounds the Cape on all sides, thereby making it an island of human construction,” he said.

“I guess one concern is that portions of what is technically known as the Cape are north of the canal (in Bourne and Sandwich), but the land that most of us live on would technically be an island.”

Ah, yes, that pesky Cape Cod Canal — 17.4 miles long, 480 feet wide, 32 feet deep. Completed in 1914 and shortening the shipping distance between Boston and New York City by 75 miles, according to Enclyopedia Britannica, which, incidentally, describes Cape Cod as a “hooked sandy peninsula of glacial origin …”

Larry Rosenberg, chief of public affairs for the U.S. Army Corps of Engineers, which is responsible for the operation and maintenance of the canal, said he sees the “island-or-peninsula” question being debated for years to come.

“I personally believe that many folks on the Cape are self-identifying it as an island, when, in fact, the geographical structure would make it a peninsula,” Rosenberg said. “But what can I say, I’m from Philadelphia.”

As for the Cape meeting the technical definition of an island — a land mass not as large as a continent, surrounded by water, according to Webster's New World College Dictionary — Rosenberg said, “Yeah well, technically, there are dredge disposal sites off China that are nearly islands, too. The wonderful thing about mankind is that we get to shape the environment.”

Peter Mcgarvey, a self-described wash-ashore from Philadelphia who lives in Dennis, posed this week’s question and said he believes the Cape is “a man-made island.”

Andrew Gottlieb, executive director of the Association to Preserve Cape Cod, leaned toward option No. 3.

“It’s a Cape," he said, referencing the National Geographic Society’s definition: a high point of land that extends into a river, lake or ocean. “I think you can take your pick, whether you say it’s a cape or a peninsula. I’ve never really thought of us as an island.

“I think it’s a psychological island in some respects,” Gottlieb added. “People feel a little disconnected from the rest of the world, in many respects for the better.”

In terms of what would have become of Cape Cod if the canal were never built, Ashton said, “It would take centuries, even with current faster rates of sea-level rise, to completely naturally form an island.” Even then, however, it’s possible that “waves would build barrier spits that would connect back to the mainland.”

Ashton tossed out this gem for some perspective: “About 6,000 to 8,000 years ago, (when) the ice age glaciers were melting and sea level was much lower, Martha's Vineyard and Nantucket were peninsulas connected to the Cape.”

Try running that one past the dartboard crew. And don't forget to duck.