Teelow, 24, fell from her skis shortly after starting the Bridge to Bridge Water Ski Classic yesterday morning and reportedly suffered critical spinal and neck injuries and traumatic cardiac arrest.

It was also reported Teelow was travelling of speeds up to 140km/h when she fell and was airlifted to Royal North Shore Hospital.

Ski Racing Australia chairman Rick Love said it was not yet known what caused the accident.

"The conditions were very good, it was on open water and the seas were slight," he said.

"We are fairly certain she didn't hit anything.

"We know she is in a very critical condition."

The race, which was put on hold for a short time, continued later in the day.

Mr Love said there was no presentation at the end with competitors and organisers instead praying for the injured waterskier and her family.

In a statement, Ski Racing Australia said it was "very proud" of its response teams, who were on scene immediately.

Darren Patterson, who was in the boat observing Ms Teelow, described her as dedicated.

"...a uni student, very dedicated to everything she does, very committed, a lovely person," he said.

In September Teelow was crowned world champion after winning the Formula 2 category at the World Water Ski Racing Championships in Spain, a win made even more special after returning from a broken ankle suffered more than 12 months earlier.

Teelow is the daughter of two-time world champion Tania Teelow and started skiing in 2007 as a 13-year-old at Burrendong Dam and made her first Australian team two years later as a junior, placing fourth at the 2009 world championships in Belgium.