Hundreds of international runners have converged on Rotorua ahead of tomorrow's Tarawera Ultramarathon - with the event expected to be watched by millions around the world.
Tomorrow's event will inject well over $1 million into the local economy but organisers say the major spinoffs include the huge media attention from around the world.
Race director Tim Day said there would be 405 international runners lining up on the start line of the sold-out event.
That equates to above 40 per cent of the field of just over 1000 runners who will take part in one of three distances ranging from 60km to 100km, running between Rotorua and Kawerau.
Mr Day said 50 nationalities were represented with athletes coming from 38 different countries.
He said each competitor brought about three people.
"For a race of about 1100 there are about 4000 or 4500 people."
The event regularly attracts international media attention, screening in dozens of different countries. An economic impact report into the 2014 event showed it injected $1.08 million into the local economy.
Mr Day said given the growth of the event since then, that figure would be higher now.
Many of the competitors stay between three days and three weeks and spend money in the community on food and drink as well as essentials.
This year the world's trail running royalty are also coming to Rotorua - with seven international race directors from the Ultra-Trail World Tour in New Zealand for the first time.
Directors and representatives from four of the 12 world tour races, including the world's largest ultra race, the Ultra-Trail du Mont-Blanc in France, are in Rotorua to learn more about what makes the Tarawera Ultra so unique.
Ultra-Trail du Mont-Blanc directors Michel and Catherine Poletti are founders of the Ultra-Trail World Tour, and Mr Poletti is also president of the International Trail Running Association.
"We approached the Tarawera Ultramarathon three years ago to be part of the world tour because we thought it was important to add to the community of beautiful, truly unique races around the world. All the races are different and it's important to learn from each other to create the best races possible," said Mrs Poletti.
Tarawera Ultramarathon organiser Paul Charteris said it was a fantastic opportunity for New Zealand and the Tarawera Ultra to have international directors present.
The race starts at 6am at the Redwoods Visitors Centre.
The top runners are expected to finish the 100km in about eight hours.
* Starts 6am tomorrow, The Redwoods
* Three distances - 60km, 85km and 100km and relay option
* 405 international runners
* Sold out with more than 1000 competitors
* Event was first held in 2009