Two under-prepared trampers who got lost in Golden Bay in bitterly cold weather over the weekend "put themselves and their rescuers at risk", say police.
The pair, a Christchurch man and woman in their mid- to late-20s, entered the Boulder Lake track near Takaka late on Saturday afternoon and became lost in darkness and horrendous weather.
The trampers became wet and freezing, and one tramper developed hypothermia. The pair called police about 8.30pm.
Searchers were able to locate the trampers' exact position using "mobile locate" technology and rescue teams were dispatched.
The Nelson rescue helicopter had to be called in due to the pair's remote location and the deteriorating conditions.