Westport man Maxwell MacDonald went for a birthday swim in the Buller River, only to be swept away downstream.
Jet boats, kayakers, police and Land Search and Rescue spent hours looking for MacDonald, 57, on Saturday until 11pm, without success.
MacDonald - known as Max - was the best swimmer in his family, Fairfax reported, and had gone for a birthday dip when he got into difficulty in a strong current.
The Police National Dive Squad found his body on Monday morning.
He leaves behind two children in Australia, Fairfax reported, where he had also been living for around 15 years.
MacDonald was travelling from Westport to Motueka with one of his brothers when he decided to go for a swim, Fairfax said.
Zane MacDonald told Fairfax the current must have been strong.
"Of the whole family, I've said he's the best swimmer of the lot of us and we've all been swimming since we could walk, almost," MacDonald said. "So it must have been a strong current to get him."
The family was very grateful for the efforts of police and volunteers that helped in the search, MacDonald told Fairfax.
A funeral will be held at Kereru Marae near Levin on Sunday.