PLYMOUTH (CBS) – A family boating trip took an unforgettable turn with a shark sighting that was caught on video.

Despite growing up on Cape Cod Bay, siblings Sean and Serena Colbert and their cousin Mallory Fey are still wide-eyed about their Friday afternoon encounter.

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“It definitely wasn’t scared of us,” said Serena Colbert.

They were about halfway back from Provincetown on a 22 foot boat.

“It was like the biggest thing I’ve ever seen,” said Mallory Fey. “That is a massive creature.”

“It was huge,” Serena said. “It seemed like it was the size of our boat.”

Sixteen or 17 feet is their guess as the great white shark and the folks on-board flirted with each other for several minutes.

Sean was just about to take a dip when they first spotted the dorsal fin.

A shark encounter off Provincetown. (Image credit: Mallory Fey)

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“Seeing it on TV you don’t realize how massive and quick it is,” Sean said.

No surprise there were several more great white sightings on the Cape Monday and even the beaches in Plymouth were closed for an hour-or-so when a great white snatched a fisherman’s catch right off his line as he was reeling it in.

And some Harbor Cruise workers spotted a great white in the bay off Barnstable.

“It was pretty graceful the way it was swimming around the boat, it was pretty cool,” Serena said.

On Monday night, there was still adrenaline in the voices of three young boaters.

“Once in a lifetime thing honestly,” Sean said.

“Just to see it in person was unbelievable,” Serena said.

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“Might have been one in a million but it was pretty surreal,” Mallory said.