Australian Sarah Teelow, 21, came off her ski in the opening moments of the Bridge to Bridge Water Ski Classic on the Hawkesbury River Sunday, sustaining serious spinal and head injuries.
She was airlifted to hospital but died on Monday evening.
Ski Racing Australia described Teelow, who won the Women’s World Formula Two championship in the Canary Islands in September, as “one of the sport’s most accomplished young competitors”.
“The ski racing fraternity is deeply saddened by Sarah’s passing and extends its condolences to her family,” it said in a statement.
“Ski Racing Australia is cooperating with police and maritime authorities in their investigations.”
Skiers can reach speeds exceeding 130 kilometers per hour (80 mph) in the 112 kilometer race. Ski Racing Australia said it did not know what caused the accident with conditions good and the sea slight at the time.
Police are investigating.