THIS is the terrifying moment a "great white shark" nearly knocked a father and son out of their small boat while they were sightseeing.

       The heart-stopping footage was filmed while dad Sean Vinar and his son James Vinar were watching sea lions off the north coast of Tasmania.

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       The moment the 'great white' slammed its tail on the surface of the water Credit: YouTube 3

       Sean and his son travelled to the north coast of Tasmania to watch sea lions 3

       The great white rammed against the family's boat Credit: Getty

       The pair had decided to visit a seal colony off Tenth Island which is 10km off the coast due to the calm water and good weather.

       "We'd never been to the island before and we thought we'll go and have a look and film some seals, have a bit of a look then continue on and do some bottom fishing for flathead," Sean told ABC.

       Sean, who has been fishing in the Tasmanian seas for 20 years, had driven their boat around the island before noticing that the seals were coming towards them.

       And it is then that James took out his phone to film the herd of sea lions.

       But suddenly, the pair were nearly thrown off their boat by a huge smash.

       "All of a sudden, we just had this mighty thump on the side of the boat, water flying through the air," Sean recalled.

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       The pair immediately sped away but it is then that a huge shark tail came out of the water and smashed down.

       According to Sean, it was a great white shark that had rammed into their small boat.

       "In a bit of shock, I've looked up towards the front of the boat and there I can see a massive big, great white shark has come out of the water and opened its mouth and latched on to the front of the boat where the anchor is.

       "It's completely engulfed the anchor we've got on the front of the boat."

       The footage was filmed last July but has resurfaced due to the recent number of shark attacks in Australia.

       Last month, a surfer was fatally mauled by a shark off Emerald Beach in Coffs Harbour, Australia.

       Four ambulance crews and a rescue helicopter rushed to the scene after the man appeared to have his arm torn off in the savage attack.

       Another surfer has undergone eight surgeries and spent two months recovering in hospital after his arm was ripped to shreds by a great white.

       Joe Hoffman, 25, had a near-fatal encounter with the deadly beast on July 5 off of the picturesque Killick Beach in New South Wales.

       Speaking to ABC News, Joe admitted that the conditions that day were particularly "sharky looking".

       This was due to it being in the late afternoon, 4:30pm to be exact, and whale season.

       But the 25-year-old said he and his friend, who had travelled more than 290 miles from Byron Bay, were willing to take their chances.

       In just ten days, Joe went underwent eight surgeries - spending more than 30 hours in the operation theatre.

       It is unknown if Joe will ever have full mobility of his arm again but the surfer is optimistic.

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