When boater Kie Crawford saw the dorsal fin moving through the calm waters off Dipper Harbour, he had to get up close.

"That thing's huge … look at the size of it!" Crawford can be heard saying on a video taken as he approached what turned out to be a shark at least five metres long.

On board the boat, his children, eight and five years old, seemed to think their father was reckless.

"What the heck! No! Dad!" they shouted.

The video, taken on the boat and featuring Kie Crawford's colour commentary, has been watched 8,000 times in the past two days.

"We were just out sailing, looking for sea dogs or porpoises for the kids," Crawford said. "Sometimes I'll look in the water to see if there's anything like buoys, just kind of beachcombing."

17-foot shark spotted in waters of Dipper Harbour0:43

But instead of buoys, Crawford spotted two fins sticking out of the water, a tell-tale sign of a shark, although one of the Crawford kids thought this meant there were two sharks — an adult and a baby.

'That's not a baby that's huge!" Crawford said on the video.

Danielle Dion, a naturalist and researcher for Quoddy Link Marine, confirmed after watching the video it was of a basking shark. She said they are commonly confuse with white sharks.

"Easiest way to tell the difference is the shape of the dorsal," she said, noting the round fin visible in the video. 

"A white would be pointed at the tip/apex of the dorsal fin."

Crawford had suspected the fish was a basking shark. It appeared to be 16 or 17 feet long.

"His dorsal and his tail fin were out of the water, and he was still quite deep," Crawford said. "The other sharks don't have that long of fins that would be indigenous to this area."

The shark was spotted about 3 p.m. just east of Dipper Harbour, about 43 kilometres down the Fundy coastline from Saint John.  

It's a good sightseeing spot for people eager to see a shark, Crawford said. They might even see the shark that got his family's attention.

"This fella here, I think he's staying around there, getting lots of feed," Crawford said. "I saw him earlier in the lobster season."