"The New Zealand Dive Squad is on its way, and at the moment I foresee them being in the water [Monday] morning."
Newell said there was large public involvement in the operation.
"It's been a big community effort.
"They have got behind this and worked together to try and find this person."
The man wasn't wearing a PFD (personal flotation device) at the time of the accident, Newell said.
"The whole lesson out of this is if you're fishing on rocks, have a life jacket."
Police were initially called at around 11.15am on Saturday, with a helicopter, coastguard, surf lifesaving and police search and rescue trying to locate the man.
In a statement on Saturday, the Wanganui Surf Lifeguard Service said it had a squad of eight surf lifeguards, with two IRBs (inflatable rescue boats) and one ATV, responding to the incident.
South Taranaki district councillor Brian Rook said on Saturday the man was about 30 and from South Taranaki.
He had been told the man initially resurfaced after being washed into the sea.
"Him and a mate were fishing at a spot called Snapper Rock.
"He got washed off the rock and was swimming back to the beach when another wave pushed him under.
"Its tragic."
Family and friends of the man, along with Waiinu Beach residents, had also been searching the shoreline in four-wheel-drive vehicles since the man disappeared, Rook said.