It's an old sea tale with many tentacles — octopus tentacles, that is. A Staten Island Ferry accident some 50 years ago claimed the lives of more than 400 people, or did it? Borough Reporter Amanda Farinacci has the fishy details:

Overlooking the murky waters of New York Harbor — a memorial to one of the most mysterious boating accidents in maritime history.

Dedicated in loving memory, the monument reads, to the passengers and crew of the Cornelius G Kloff, who lost their lives on November 22, 1963:

"I had no idea," said one man. "But I don't even remember hearing about it."

That's because it didn't happen. Staten Island prop artist Joe Reginella created the five-foot monument as, he says, a social experiment.

"See if I could create an urban legend and see if people would buy it," Reginella said. "And it's also a social experiment; see how many people would believe it."

That was certainly true when NY1 visited the memorial on a recent morning.

"At least you have some memories of people who came here and were lost their lives," said one passerby.

"That's nice," said another. "A ferry boat, swallowed by an octopus. Ok, I understand that, yea."

According to the story Reginella created — the Staten Island ferry boat was heading toward the Whitehall terminal with nearly 400 people aboard, when it disappeared — never to be seen again.

Witnesses describe seeing "large tentacles" that pulled the boat below the surface.

To reinforce the hoax — Reginella created a Facebook page, and a website commemorating the make-believe disaster:

Reginella got an angry call from the Staten Island Museum, where people have tried to visit a ferry disaster museum there:

"I just think this is a horrible joke; you've got people misled," said a voicemail message left for Reginella.

Most people we caught checking out the memorial stopped, took a picture and moved on.

Just a handful expressed any doubt about the facts surrounding the Staten Island ferry octopus disaster.

"I don't think there was a giant squid in the water," said one skeptic. "I don't think so."

"It's an octopus?" asked another incredulously. "That's it's some sort of a, some sort of a joke."

Reginella says he's observed about 90 percent of the people believe his hoax, something he says makes him happy and dubious at the same time.