In the annual jet-boat race, which forms part of the Southern Inter-provincial Jet-boat Race series, 23 high-powered boats will take on a 60km course from the State Highway 1 Waitaki River bridge to Kurow.
Race organiser Tim Guthrie said the braided-river course would be even more difficult than usual because of snowmelt.
The race starts at 9.30am. A spectator-friendly circuit race is planned for this afternoon, with good viewing for those using four-wheel-drive vehicles from Te Maiharoa Rd on the Glenavy side of the river.