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.