UPDATE: The body of the missing deckhand has been recovered.
The man was found by Navy divers, said police.
Inquiries would be made into the circumstances of the man's fall by WorkSafe and police.
Earlier: Navy divers have joined the search for a deckhand who fell overboard from a ship berthed at the Port of Tauranga this morning.
The man, believed to be a Chinese national, fell 10m into the harbour and did not resurface about 9.20am today.
Police and Coastguard searched for the man without success.
A navy ship happened to be in port at the time and navy divers have joined the search.
Senior Sergeant Karl Konlechner of the Bay of Plenty District Command Centre said it appeared to be "a tragic accident".
"The search has yet to locate the man but divers are now looking for his body. The police are very grateful for the prompt response from the NZ Navy personnel who were in the port at the time and quickly joined the search."
Coastguard Tauranga skipper Chris Clark said Coastguard has had one boat searching the harbour for the man since 9:45am.
"We're working alongside police and the local harbour master."
He was unsure of details of what had happened but said Coastguard would continue to search as long as police instructed.
A Port of Tauranga spokesman said they were aware of the incident but referred queries to police.
"It is a police-led operation. We don't have anyone specifically involved in the search."
Police divers are also on standby.
WorkSafe have been advised of the incident.
Police are also searching the Waikato River for a man after his clothes and dog were found on the river bank.
Searchers have been out searching the river and the surrounding areas since last night, Senior Sergeant Robbie Hermann of Waikato police said.
"He's a missing person as some clothes and his dog were found near the river so we think he's gone into the river."
Mr Hermann said the man was European and 178cm tall.
The police boat was searching the Wellington Street Beach area this morning, he said.
Anyone with information about the man's whereabouts is urged to ring Hamilton police on (07) 858 6200.