More than 8000 people are expected to compete in the Auckland Marathon today.
The 2021 event, which was due to be held in October, was postponed due to Covid-19 restrictions.
The event started at 6am with the full marathon and wheelchair marathon at 42.195km and the half marathon at 21.1km.
Under the orange setting, all competitors are required to be fully vaccinated to compete.
There are additional hygiene measures in place at the event and the finish line at Victoria Park is fully fenced, with spectators and competitors required to show their vaccine pass for entry.
IronMan New Zealand regional director Amy MacCormack said a number of changes had been made so the event could meet the requirements under the orange setting.
"It does require a bit of additional Covid overlay in terms of what operations look like to our 'business as usual' and that means additional hygiene practices and in particular I guess creating designated event spaces whereby we're protecting members that are not double vaccinated from client groups that are."