Mrs McHale and her husband Ben, a doctor, lived in Rarotonga last year.
Local triathlete Taki Anaru told the Cook Islands News that it was a terrible tragedy for the triathlon community on Rarotonga.
"Stephanie had represented New Zealand as an age grade triathlete and was third in the Round Rarotonga Road Race last year. A great athlete," he said.
Remembering their recent visit for the triathlon, Mr Anaru said Mrs McHale was pregnant by that stage so did not race but was there yelling Ben on from various points on the course.
"The tri community is in total shock and are devastated about this terrible accident. A very sad and sombre day for all of us."
Mrs McHale will be farewelled today with a funeral service at the Rotorua Convention Centre from 11am.