In the May event, firefighters will compete in teams and as individuals for the fastest ascent, but also to raise funds for the Leukaemia and Blood Foundation.
Ten firefighters from the Arrowtown and Frankton volunteer fire brigades, and two support staff, have joined forces this year to train and fundraise.
Arrowtown firefighter Chris Tate, training for his second challenge, is aiming to up the ante.
"We think we can probably do a bit better this year, training a bit differently and concentrating a bit more on cardio stuff, rather than strength. We just did stairs when we probably should have been doing a bit more running and cycling."
Fitness is important during the climb, as the firefighters breathing through masks struggle to get enough air into their lungs.
"Your lungs burn. Man, they burn ..."
The structural firefighting kit the firefighters wear includes gumboots, breathing apparatus and an air tank and a heat resistant suit, which also seals in the heat and sweat from the climb.
In total, it weighs about 25kg. Mr Tate described the challenge as "killing".
"It went on forever ... You're trying to block out how many flights there are and you look up and you're at eight, when you're trying to get to 51. It's hard, you're hot and you're trying to get as much air in your lungs as you can."
This year, about 420 firefighters from brigades all over New Zealand and all age groups - the oldest is 61 - will compete.
