Up to 1000 athletes will take on The Taniwha today.

The inaugural event will see walkers, runners, cyclists and teams racing as little as 7km and as much as 80km along the Waikato River Trails that form part of the national cycleway.

Forty per cent of entrants are from Auckland, another 40 will travel from Hamilton, Taupo, Rotorua and Tauranga.

The rest live near the trails that run along previously inaccessible land from Karapiro to Whakamaru, as well as South Islanders and Australians.

Like the other long distance categories, it begins downriver from the communal finish line at the Whakamaru Christian Camp.

Event organiser Dave Franks said one of The Taniwha's aims is to expose the little known beauty of the trails that snake along New Zealand's longest river.

He had hoped to attract 600 competitors but he's stoked to get 800.

"You can't help but look, even if you're racing.

"The views and everything are just awesome, especially if it's a nice day like it's meant to be - it'll be magic."

The course is designed to be achievable for everyone.

It runs along boardwalks, swingbridges and gravel sections yet it should still be a challenge for more experienced athletes.

Mr Franks said the event has been embraced by local businesses and authorities and will have economic benefits for the area.

It will also become a permanent fixture on the events calendar, he said.

- © Fairfax NZ News