Maybe it's protesting about something, given it's up by the Houses of Parliament currently
http://news.bbc.co.uk/1/hi/england/london/4633376.stm
Rescuers are growing increasingly concerned for the safety of a seven-tonne whale, stranded in the River Thames in central London.
Riverside crowds gathered throughout the day to watch the 16-18ft (5m) northern bottle-nosed whale swim as far upstream as Albert Bridge by Chelsea.
Experts fear it may become beached when the tide changes, or could be put down overnight to prevent further suffering.
Specialist equipment was being used to try to redirect the animal downstream.
The whale, usually found in deep sea waters, has come within yards of the banks and has crashed into an empty boat causing slight bleeding.
Since darkness fell it has been harder to monitor the whale's location, but there are reports suggesting it may have made some progress downstream.
Alan Knight of the British Divers Life Marine Rescue Group said they would continue attempts to keep the whale in view.
It is a very unusual thing and we have never done it before with a whale this size - it might float, it might not
Alan Knight, of the British Divers Marine Life Rescue group
Watch the whale
Whale in pictures
He said they had strong floodlights on the boat and they would "carry on and stay on the river as long as necessary and do all we can."
Vets are remaining on standby and experts have said it does not appear to be ill, but are concerned it will get weaker and may become beached.
Mr Knight said if the whale does goes ashore, teams could then check its health.
He said if it appears thin, it may be coming in to die, and added: "In which case we will euthanize it and consider it a success because it has not caused more suffering."
If well however, a system of pontoons will be used to try to refloat it by lifting it into a boat and taking it out to sea, he said.
Click for Northern bottle-nosed whale factfile
"It is a very unusual thing and we have never done it before with a whale this size. It might float, it might not."
He added that the whale was damaging itself by coming ashore.
The RNLI say it is the first whale rescue on the Thames. A spokesman said three whales were spotted east of the Thames Barrier on Thursday but only one managed to get upstream.
But at 0830 GMT on Friday, a man on a train called in to say he might have been hallucinating, but he had just seen a whale in the Thames.
Plans to rescue the whale
Crowds flock to riverbank
Alison Shaw of the Marine and Freshwater Conservation Programme at London Zoo, said the northern bottle-nosed whale was usually found in groups of three to 10.
She told the BBC News website: "This is extremely rare in British waters as they are normally found in deep waters in the North Atlantic.
"It is about 16-18ft long, so is relatively mature. It is a very long way from home and we don't know why it has ended up here."
The whales usually weigh about seven tonnes, which will complicate any rescue attempt, experts said.
Over the years dolphins and seals have been spotted in the Thames.
Sperm whales have been seen in the Thames Estuary and porpoises have feasted on fish near Vauxhall Bridge, in central London.
Hyperoodon ampullatus
Adult length: 7-10m (23-33ft)
Weight: 5.8-7.5 tonnes
Diet: Squid, fish
Habitat: Deep offshore waters
Range: Arctic and North Atlantic
Status: Lower risk, conservation dependent, protected since 1977
Distinctive feature: Bulbous forehead
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