Rotorua swimmer Kane Radford is the front-runner in the men's field for the Epic Taupo 10km swim as he makes a bid for the London Olympics.
Radford, who won the opening round of the State Ocean Series in Auckland, also won the famed Tiburon Mile in San Francisco last year for the second time.
The New Zealand team member for the 2011 world championships in Shanghai spent last month training at altitude in the United States. He is expected to lead the men's field as the current Australian 5km champion.
The other Kiwi contenders include Auckland's Phillip Ryan, the defending national champion and 2009 champion; Casey Glover (Queensland-based); and Stefan Talbot (Howick Pakuranga).
The Australian challengers include Trent Grimsey, a former world 25km silver medallist, and Australian junior champion Josh Richardson. Phillip Rush, Swimming New Zealand open water manager, said it was an important weekend for the open-water swimmers.