Experts say a whale spotted blowing water in Dublin Port is confused, stressed and will most likely die.
Teams are trying to figure out what type of whale it is, after it was first noticed by walkers at Sutton Beach on Tuesday.
Since then, it has moved to between boats and ships at the mouth of the Liffey.
Dr Simon Berrow from the Irish Whale and Dolphin Group says it is extremely rare for a whale to be in those waters.
"It looks like an immature, it looks small, about 30-40 foot and it is probably in poor condition," said Dr Berrow.
"It is presumably disorientated and I would say it is probably going to die anyway.
"To enter the port harbour docks area is unusual.
"It will be stressed, it will be disorientated so it might need some help to exit the area.
"But even if it does, it probably will end up stranding and dying."