The search for missing tramper Stephanie Simpson in Mt Aspiring National Park is continuing today, with search teams remaining out in the area overnight.
The search began on Monday morning after the 32 year old - who is on a working holiday from Essex, UK - did not return to work and her friends did not know where she was.
Otago Daily Times reported her parents would be flying to New Zealand to help with the search. Her brother-in-law Sam Hazelton told Sky News the family were all worried and desperate for information.
He told the network the last time the family had heard from her was early on Thursday morning.
"She contacted her friends after that on the Friday to say she was going hiking and camping ... this was something Stephanie would do most weekends, it was her main reason for staying in Wanaka in New Zealand as it offered so many different trails.
"Stephanie is very competent and physically fit. She is relatively experienced in outdoor activities and has already completed a number of hikes. She is such a fun-loving, kind, determined and adventurous woman, we are asking anyone who might know anything to please get in touch with police," Hazelton said.
A friend said Simpson's family would be travelling to New Zealand to help in the search.
A police spokesperson said drones with thermal imaging would be deployed - along with search teams including local Land Search and Rescue and a helicopter - this morning.
They said the search would continue to focus on the area from Fantail Falls to Mt Brewster, the Brewster Hut and Mt Armstrong track, and also Makarora Valley but it was complicated by the large search area, much of which was difficult terrain.
Anyone who stayed in the Cameron Flat area on Friday and saw or spoke to Simpson, or anyone who may have seen her on the track from Fantail Falls to Mt Armstrong or in Makarora Valley, was asked to contact police.
Simpson's boss told RNZ yesterday she was very fit and healthy and had the experience and equipment for tramping.
Two people were found dead in the national park over the weekend, but police said they were not believed to be connected to the missing person search.