The impact of four deaths on a family-friendly Dreamworld ride in 2016 is still being felt by the theme park's owners, who have written $75 million off the value of the embattled Gold Coast business.

Dreamworld's parent company Ardent Leisure made the announcement in a financial update to the Australian Stock Exchange (ASX) on Monday.

The latest writedown follows last year's FY17 value decrease of $89 million.

Ardent Leisure estimates its revenue to June 26, 2018 is between $545 million and $550 million, and its after-tax loss will be between $84 million and $94 million.

The company said the revaluation adjustment for Dreamworld reflected a slower recovery in attendance at the theme park than previously projected after the ride tragedy.

Discounted ticket pricing and adverse weather conditions were also reasons given to the ASX for the revenue losses.

The theme park has struggled since four people were killed on the now-decommissioned Thunder River Rapids ride on October 25, 2016.

Cindy Low, Kate Goodchild, her brother Luke Dorsett and his partner Roozi Araghi were killed instantly when the ride malfunctioned.

Two children on board managed to escape.

The Thunder River Rapids Ride has now been decomissioned. ( AAP: Dan Peled )

The tragedy led to the park's closure for six weeks while investigators examined the ride and the park's other amusements were audited.

Then-Ardent chief executive Deborah Thomas resigned in the months after the incident.

An inquest into the Dreamworld deaths began on the Gold Coast in June and has been adjourned until mid-October.

Dreamworld chief executive Craig Davidson, who was in charge of the park when the ride tragedy happened, announced last month he was leaving the company.

Ardent intends to report its full year results on the FY18 on August 22.