He has been identified as Eli Sweeting from Bristol, who lives at Port Motueka, Tasman.
His sister Serena Sweeting, from England, posted on social media that this was an ‘‘incredibly worrying time’’.
‘‘I feel so hopeless being so far away but it's reassuring the effort going in to [finding] him.’’
She said Mr Sweeting’s family and herself were all very thankful to the police and search and rescue teams working so hard to find him.
On Sunday, Mr Sweeting was solo-tramping on a planned day trip to Mitre Peak in the Fiordland area.
However, the alarm was raised when he failed to return.
Search and rescue operations began just before midnight on Monday and have continued into Wednesday.
Detective Tracy Ward said Mr Sweeting was an experienced outdoorsman and police believed he had suitable clothing and provisions, ‘‘which can make all the difference’’.
Last night there was a deterioration in the weather that affected ongoing searches.
This morning, it was only ground crew able to search as weather conditions halted helicopter flyovers.
She said a large number of resources had been working through arduous terrain, assisted by helicopter crews.
Supporting police in the search were Land Search and Rescue teams from Fiordland, Caitlins and Southland, Southern Lakes Helicopters, Heli-Otago, Southland Amateur Radio Emergency Communications, a Wakatipu Land Search and Rescue tracking dog team, a Dunedin Land Search and Rescue air scent dog team, and Wakatipu Alpine Cliff Rescue teams.
There were also roughly 60 volunteers, 10 police staff and local tourism operators assisting.
‘‘Land Search and Rescue field and dog teams have been in the search area since Monday morning, as well as alpine cliff rescue teams due to the incredibly steep terrain in the area,’’ Det Ward said.
Tourism company Real NZ has assisted the operation with marine vessels and support staff, as well as helping the search staff at the forward control base in Milford Sound.
‘‘We are looking at a wide search area in a very rugged part of New Zealand. We have yet to find any items that could help narrow the search area, but we are remaining positive.’’
Police have spoken to many people who encountered the man in the vicinity of Mitre Peak on Sunday.
If anyone in the area on Sunday had not yet spoken to police, Det Ward asked them to call 105 and reference the number P06244822.
