The family of mother-of-two Cindy Low say they are still learning to live without her a year after she was killed in the Dreamworld accident.
"Our grief has come in waves but the firsts are especially hard - birthdays, Kieran and Isla's milestones achieved that she does not get to experience," her husband Mathew Low told the Courier-Mail.
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New Zealand-born Ms Low was killed alongside Kate Goodchild, Kate's brother Luke Dorsett and his partner Roozi Araghi when the Thunder River Rapids ride malfunctioned. Her son Kieran was thrown clear.
Ms Low was from the Bay of Plenty in New Zealand but lived in Sydney with her young family, and Mr Low said they had spent the past year trying to come terms with their loss.
"We have spent each week and month comforting each other and learning how to live without her," he said.
"Her irreplaceable presence in our lives is immense. We miss her so very much."
On the eve of Wednesday's anniversary, the mother of Ms Goodchild and Mr Dorsett revealed her ongoing despair.
"Their deaths have certainly left a hole in hundreds of lives, but none so much as mine, Kate's girls and her loving partner," Kim Dorsett told News Corp Australia on Tuesday.
Dreamworld staff will hold a private ceremony to mark one year since the fatal accident.
The Gold Coast theme park was closed for 45 days following the tragedy.
An inquest into the disaster is yet to be held, while a Workplace Health and Safety Queensland report has been completed but not publicly released.