Police investigating reports of a man in the River Lagan have been contacted by a member of the public claiming they saw someone emerging from the water.
A search operation began at 1600 BST on Saturday after the emergency services were told a man had been seen in the water near Queen's Bridge in Belfast.
A third day of searches will begin at first light on Monday.
Police are looking into a report a man was seen coming out of Belfast Lough at Whitehead between 1700 and 1730 BST.
A member of the public said a man, who matched the police's description, was seen about six miles along the coast, walking towards Newtownabbey.
A police spokesman said the man was believed to be carrying a backpack and was wearing dark-coloured clothes.
Appealing for information, he said anyone who either saw someone matching that description or who was missing a loved one should contact police.
The police helicopter and divers went to the scene on Saturday afternoon and the Lagan Weir was closed overnight.
It is understood the river bed and the surrounding area was dragged by Belfast Harbour Commission.