The Tarawera Ultramarathon has injected more into the local economy than ever before, with latest figures showing a $1.2 million spinoff for Rotorua and Kawerau.
The high number of international participants and their "disproportionately large" spend is what organiser Paul Charteris thinks is behind the jump. And with growing interest from overseas competitors, it may get bigger yet.
Mr Charteris said while the report into the economic impact revealed February's event brought in $1.2m net contribution into Rotorua and Kawerau and a further $1.9m to the New Zealand economy, the real benefit was even wider.
He said the huge media coverage of the event on a picture-perfect day generated publicity around the world that money couldn't buy.
This year half of the 1350 runners who took part were from overseas, Mr Charteris said.
"International runners were from 42 countries and each spent more than twice as much as each domestic runner while they stay in the Rotorua area. On average, each runner brought two extra people with them and stayed three nights in Rotorua."
Mr Charteris said as the reputation of the event had grown, the number of international runners had swelled from 85 in 2014 to more than 600 this year.
"Almost all of that growth has been word of mouth rather than any specific overseas marketing push. We have a unique combination of clean lakes and rivers together with a variety of native bush and planted forest that cannot be found in many parts of the world."
Mr Charteris said he thought future events would attract even more international participants.
"It's extraordinarily high right now."
Mr Charteris said it was difficult to put dollar value on the media exposure, visitor experiences and imagery that came out of these events.
"The media is huge but to try and put a dollar value on that is so hard.
"It's absolute gold.
"This year's race was held under perfect conditions so we generated more than 25,000 photos and hours of video coverage. These have been viewed around the world millions of times."
Deputy Mayor Dave Donaldson said Rotorua had always been recognised as delivering quality events and the ultra stood out as one of those.
He said it wasn't just about the direct economic impact but the international visitors who went away and told good stories about their time in Rotorua.
"The Tarawera Ultramarathon showcases some of our most stunning scenery."
He said the economic impact was "reassuring" and the benefits were widespread.