A rip caused by the outgoing tide may have contributed to the death of a swimmer at Mokihinui, 46km northeast of Westport, yesterday.
The 44-year-old Mokihinui man was swept out to sea about 3.40pm when he tried to swim across the mouth of the Mokihinui River.
His body was retrieved from the sea at 6.30pm. It was discovered about 15m from the shore in about 2m of water.
Local photographer Sheree Cargill said she was at the nearby camp ground when a man "in a panic" roared up in a truck, seeking a boat. She borrowed a kayak and two life jackets from friends. Two kayaks were already searching the river when they arrived at the beach, she said.
The tide was going out, creating a rip at the river mouth. "When the tide goes out, it's strong. You ask any local, they'd say there's no way in hell they'd go swimming when the tide's going out ... the undertow, you could see the rip underneath it."
St John Ambulance and Granity firefighters were the first emergency personnel on the scene, followed later by surf rescuers, Ms Cargill said.
West Coast search and rescue controller Sergeant Sean Judd said the man had been on a fishing trip with friends when he had decided to go for a swim and got into trouble.
Search and rescue was alerted immediately and a helicopter and two rescue boats were sent out.
Mr Judd said there was nothing particularly different about yesterday's conditions. It was a nice sunny day and the flow level was normal.
"In my opinion in any river mouth, in any river, there's always an element of danger," he said.
He said 20-30 people had helped with the search effort including Buller Surf Rescue, Granity firefighters, St John and locals.
He didn't know whether the man was a strong swimmer, but expected that, as a local, he would have been well aware of the conditions.
At this stage there was no indication that alcohol was involved, Mr Judd said.
Police hoped to name the man this afternoon, after next of kin had been informed.