It was more than 5m long and powerful enough to lift a former cray boat out of the water but five mates who had a close encounter with a great white shark north of Perth believe the animal was simply behaving like a friendly puppy.
The fishermen - skipper Mark Byass and mates Stewart Archer, Wayne Bruce, Brent Henry and Jarryd Antcliff - took dramatic footage of the shark during a fishing expedition on Sunday morning.
They set out aboard the 12.8m Apache Lass, which is co-owned by Mr Byass and Mr Archer, from Two Rocks marina about 8am and first spotted the distinct shape approach the back of the boat about 9am when they were about 5km off Yanchep and in water about 27m deep.
"We were out there fishing and out of nowhere it just came to the back of the boat, a big shark," Mr Archer said yesterday. "It was beautiful clean water, it was easy to see.
"It didn't take too long to realise, hang on a minute, with phones these days you can film it, so we grabbed our cameras."
Mr Archer said the fishermen interacted with the shark by throwing fish heads and carcasses attached to rope in its direction.
"It was placid for the first hour or so, then we started teasing it with a bit of bait, which it ate and it started getting aggressive," he said. "There was one particular one where it hit the back of the boat with its back and it yawed the whole back of the boat up and a third of its body came out of the water from its tail and belted the side of the boat.
"That was frightening. If the seas had been a bit different or someone was standing at the back there, it probably would have hit them pretty hard."
The fishermen decided to move away from the shark and try to catch fish.
But the shark followed as the boat moved to five separate locations, staying close for about three hours.
"As we took off, you could see it chasing like a dolphin behind us, it was belting along behind us . . . it was coming after us straight away," Mr Archer said.
"It fantastic to watch, seeing it in our wake, this big broad back just raging through the waves."
Mr Archer believes the shark may have initially been attracted to the boat because it had learnt it could get a feed of fish scraps but Mr Byass, whose father was a shark fisherman, has a different theory.
"Dad believed it could be a rogue shark, it could have lost its partner and was looking for another one," Mr Byass said.
"It's seen the black hull of the boat and the white, and it might have thought it was a new partner. It was sometimes right alongside the boat sitting there just trying to rub alongside it. It was placid, it was like a puppy dog. It was cruising around just checking us out."
Mr Byass said though the day's fishing was a failure, the experience was worthwhile.
Mr Bruce said he was happy to watch the shark from the flybridge on the boat, with his mates all standing on the deck and a lot closer to the animal's jaws.
"It was a good experience but I was worried," Mr Bruce said.