NEW YORK — Ever hear about the gargantuan octopus that dragged a New York City ferry and its 400 passengers to the river bottom nearly 53 years ago?

A cast bronze monument dedicated to the victims of the steam ferry Cornelius G. Kolff recently appeared in Battery Park at the southern tip of Manhattan, erected a stone’s throw from a handful of other somber memorials to soldiers, sailors and mariners lost at sea or on the battlefield.

But if you can’t recall the disaster, it could be because the artist behind the memorial, Joseph Reginella, made the whole thing up.

The 250-pound monument, which depicts a Staten Island ferry being dragged down by giant octopus tentacles, is part of a multi-layered hoax that also includes a sophisticated website, a documentary, fabricated newspaper articles and glossy fliers directing tourists to a phantom Staten Island Ferry Disaster Memorial Museum across the harbor. It took Reginella six months to put it together.

He said the idea for the project came to him while he was taking his 11-year-old nephew from Florida on the ferry between Manhattan and Staten Island.

“He was asking me all kinds of crazy questions like if the waters were shark-infested,” he said. “I said ‘No, but you know what did happen in the ’60s? One of these boats got pulled down by a giant octopus.”

“The story just rolled off the top of my head” and the idea for a mock memorial was born.

It evolved to become “a multimedia art project and social experience – not maliciously – about how gullible people are,” said Reginella, who creates artworks for store windows and amusement parks.

There really was a Cornelius G. Kolff ferry. It ferried passengers for 36 years before becoming a stationary floating dorm for Rikers Island inmates. It was sold for scrap in 2003.