A mountain-bike competitor died during Saturday's Macpac Motatapu multisport event.
A police media spokeswoman said the 65-year-old man was seen to collapse by other competitors, and died a short time later.
Police were notified just before noon after a personal locator beacon was activated by another person at the scene.
She could not say where on the course the man died, but a helicopter was used to take the man's body to Frankton's Lakes District Hospital.
The event's mountain-bike course runs 47km from Glendhu Bay, on Lake Wanaka, to Arrowtown. It reaches 875m at its highest point.
The death appeared to have been caused by a medical event, she said.
A statement from the event's organisers said they were ''deeply saddened'' by the man's death.
''Our sincere condolences go out to the athlete's family and friends at this most difficult time.''
They would continue to work with the man's family and local authorities to provide support and assistance.
St John spokeswoman Victoria Hawkins said eight competitors were flown to Lakes District Hospital for treatment.
That was for a range of minor-to-moderate injuries and conditions, including a broken leg and dehydration.
