The event follows a 10km multi-lap course, with the full marathon running around it four times, while the half marathon is two laps and once around for the walkers.
They will start and finish near the Union Boat Club on Somme Parade, after crossing the Dublin St, City and Cobham bridges.
Last year's winner was Feilding's Struan Webb, who dashed home in the men's section in just under three hours, four minutes after 42km of running with the lead group.
The overall record fastest time belongs to top New Zealand runner Phil Costley.
Worth keeping an eye out for is Napier's Warren Bernard the 31-year-old clinical psychologist who will be running the second race of his goal of completing 20 marathons in 20 months.
He is fundraising for LIV Village - a charity in Africa that rescues and cares for vulnerable children.
Today walkers were starting at 6.30am, followed by the full marathon at 7.30am and the half marathon at 9am.