Ultra marathon just got tougher

Extreme fire danger means those competing in this year's Tarawera Ultra-marathon will find the course even tougher to complete.

About 430 entrants are due to take part in the 100km-long run on Saturday. The event was scheduled to run from Rotorua to Kawerau but because of the drought and fire risk, the last 40km of the course has been closed.

Organisers say instead of finishing on forestry roads in Kawerau, runners will turn around at the 60km mark of the race, next to the Tarawera Falls, and run back over rugged, hilly trails.

Event organiser Paul Charteris said the Tarawera Ultra-marathon had a reputation as being relentlessly tough, but achievable, even for a first-time ultra runner.

"I'm afraid this new course is going to break some of those runners," Mr Charteris said.

"It'll mercilessly eat them up and spit them out."

There were also shorter options over 85km and an 60km run on many of the same trails as the 100km race.

He said with more of the route covered by rocks, roots and hills, runners would need to conserve more energy for later in the race.

Mr Charteris said the decision to re-route the course was straightforward.

"The safety of runners, spectators and volunteers is always the number one priority."

The winner of the 100km event is expected to finish in about eight-and-a-half hours. The final finisher is expected home just before midnight.

Mr Charteris said it had been a hectic few days re-arranging the course.

"There's an army of dedicated volunteers putting in long hours to make sure the race comes off smoothly," he said.