Firefighters from across the country will be donning full rescue outfits and breathing apparatus, before climbing 1103 steps over 51 flights of stairs reaching a vertical height of 328 metres tomorrow.

There's no emergency. They are doing it to raise money for the Firefighter Sky Tower Stair Challenge.

OceanaGold's Mines Rescue Team have it harder than most because they use a 14kg long duration closed circuit breathing set which means the air is recycled so it gets hotter as they run.

Currently the Waihi team is in fourth place for funds raised, and team member Shay Perkinson is fifth overall on the individual leader board.

The Firefighter Sky Tower Stair Challenge is one of Leukaemia and Blood Cancer New Zealand's largest fundraising events and is in its 16th year.

The event at Auckland's Sky Tower has consistently raised more than $1 million in each of the last four years.

It's not for the unfit or faint-hearted. It is described as being challenging and demanding.

Training recommendations include running steep hills and sand dunes, rowing and weight training. Participants are also advised to wear a heavy jacket and pants whilst training in the last few weeks before the event.

The guys cooling down after training.

Shay has done the challenge twice before and says it's 'horrible” but he does it to support the cause.

'It's just super-hot, you can't really breathe.

'You've got to try shut your mind off as much as possible and not look at the numbers of the flights of stairs.”

The Waihi team has been preparing for this year's event as individuals and as a team.

They've been training in Bowentown and recently climbed Mauao, which at 232 metres, is still only two-thirds of the vertical height of the Sky Tower.

The current record for the climb is eight minutes 34 seconds, and is held by a competitor described as ‘an ironman machine'.

Members of the Waihi team aim to complete the climb in 14-15 minutes, raising nearly $19,000 in the process.