About 550 paddlers and powerboat riders braved the early morning chill for the start of the Avon Descent.
Records are tipped to tumble this weekend with water levels higher than they have been in years.
The race kicked off in Northam and finished for the day at Cobbler Pool.
Race director Jim Smith predicted some “fast and furious” racing and there were plenty of thrill and spills.
Extracts Weir, east of Toodyay, was where a lot of competitor came unstuck as they tackled the rocky obstacle.
Spectators are likely to see more gripping action tomorrow when racers reach Bells Rapids.
Competitors will then finish the gruelling event at Riverside Gardens in Bayswater.
A new king of the water will be crowned in the 42nd year of the race with the title holder not taking part.
South African Hank McGregor has won the past four Avon Descents and there are plenty of Australians hoping to take his crown.
The race covers 124km over two days and attracts competitors from around the globe.
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