There's a great white beast stalking the waters - but it's wings rather than fins you need to keep an eye on.
A section of the UK’s longest canal has been branded a no-go zone after a spate of attacks on boat users... by a thug swan nicknamed ‘Tyson’.
The 4ft tall bird - which has a whopping 8ft wingspan - viciously attacks rowers, canoeists and even walkers strolling on the river bank.
Tyson’s aggressive behaviour has got so bad that a two-mile stretch of the popular Grand Union Canal in Bugbrooke, Northamptonshire, has been branded out-of-bounds for boat users.
Keen kayaker Joe Davies, 20, a chef at a nearby pub, was captured on camera capsizing after Tyson battered him with his huge wings on Tuesday afternoon.
He said: 'He went for me as soon as I got in the water - that made me wobble in the kayak and I eventually capsized.
'He went for me as I was falling in, which really made me panic. I was terrified, it took my breath away.
'I’ve been kayaking on this stretch of canal for five years so I’m a confident boat user. I’d heard the rumours about Tyson but I’ve never seen him before.
'Basically he patrols a good two-mile stretch of the canal which is really popular with boats and barges.
'It’s a bit of a nightmare and I’m worried less able canoeists and kayakers could be really hurt if Tyson attacks them.
'You hear about the damage that swans can do when they attack people so I was bricking it, to be honest.
'I was glad to get out of the water, and I won’t be going back to that stretch of canal again.'
Local resident Linda Sgoluppi, 34, said Tyson had attacked three boat users in the last month.
She said: 'He is quite a character. He has got an aggressive side, especially as he has got a new mate and he is starting to build a nest.
'He recently forced three canoeists to get out of the water. I think all canoeists and kayakers need to be warned that he can hurt them if he launches at them.
'He is always around this stretch of the canal and he sees it as his territory. Anything that is rowed down the canal he sees as a threat.'
During the March to May breeding season, swans become very territorial and can be aggressive to any intruders.
They often threaten humans who venture too close to their nests while issuing a warning call.
In 2009, a swan was dubbed ‘Mr Asbo’ when it started attacking rowers on the River Cam, Cambridgeshire.
Earlier this month, an application was made to move the notorious swan to a spot 50 miles away to stop him attacking river users.