Christchurch's Emma Timmis smashes world record for running length of New Zealand

The world record for running the length of New Zealand has been smashed by two weeks. 

Ultrarunner Emma Timmis completed the 2100km journey from Cape Reinga to Bluff on Friday night in just 21 days. 

Now, the Christchurch-based ultramarathon runner has her feet up and is relaxing on the couch.  

"Pretty exhausted. Feeling like someone who's not slept for the last 21 days," Timmis jokes.

She set out from Cape Reinga three weeks ago and has been running a whopping 100km - or two-and-a-half marathons - every day since. 

She loosely followed State Highway 1 through the middle of the North Island before skirting down the South Island's east coast right the way to Bluff. 

There were shouts of celebration as she jogged to the finish at Stirling Point shortly after 11pm on Friday, smashing the previous world record by 14 days. 

"It's been the hardest 21 days of my life," Timmis tells Newshub.

Many of Timmis' supporters joined her on the expedition, where kids offered her moral support, police and firefighters kept her safe on her mammoth journey and supporters provided her with a much-needed laugh. 

"The gumboots have come out," Timmis jokes.

The laughter throughout her journey went hand in hand with her cause of raising funds for youth mental health.

Timmis says they had raised $5000 on Friday but that has now surged to $18,000 on Saturday afternoon, just $3000 shy of her target. 

"When I wasn't able to run, I really struggled with my own mental health and through that, I just really wanted to give back to other people that are struggling as well, in particular young people," she says. 

Her partner is incredibly proud of her after completing the incredible achievement. 

"I was proud of her before this but even prouder of her now," partner Tristan Phipps says.  

After over 2000km on the road, Timmis' next plans are simple, resting her feet and recovering. 

"Don't try this at home boys and girls," she says. 

Watch the full story above.