Every year, hundreds of people are hospitalised for hypothermia. Largely, it's a result of not being prepared.
Ever-intrepid Story reporter Lachlan Forsyth decided to get very cold in the name of education.
First, Lachlan swallowed a pill that would record his temperature. Then he sat in a stream on Wellington's south coast during a freezing northerly.
There was warm clothing ready to go, as well as a medic, a hypothermia expert and a member of the Mountain Safety Council -- just in case things turned pear-shaped.
Hypothermia expert Jim Cotter says getting wet is a big risk factor when it comes to hypothermia.
"[A] number of New Zealand streams have got slippery rocks, and you're hopping up the stream and you slip and you're straight in. You could be lying there injured and you couldn't get out."
Once wet and cold, the body's core temperature starts to drop and shaking sets in.
Mild hypothermia is when the body's core drops to 35degC. People with mild hypothermia will shiver, may appear drunk and could deny there's a problem.
The body churns through calories at a rate six times faster than normal in an attempt to keep the body temperature up.
From here, the "umbles" set in -- stumbling, grumbling and mumbling. They are often coupled with increased breathing and heart rate.
Symptoms of severe hypothermia are muscle stiffness, shivering stops, collapse, unconsciousness, cardiac arrest and even death.
For Lachlan, his body fought to keep warm for two hours before he started running low on energy. That's when his temperature dropped.
If you come across someone suffering from hypothermia, here's what you should do:
1. Find shelter. 2. Remove and replace wet clothes. 3. Assist rewarming. 4. If they are unconscious, place them in the recovery position. 5. Monitor them, and call for help.
Watch the video for the full Story report.