Dean Sanderson, 50, died and his wife Shannon, 48, was seriously injured after they plunged about 16 metres from the flying fox run by Jungle Surfing Canopy Tours at Cape Tribulation on Tuesday.

Mr Sanderson was pronounced dead at the scene. His wife was airlifted to Cairns Hospital were she remains on Thursday in a stable condition.

It is unclear what happened and Workplace Health and Safety officers have been investigating at the site at Camelot Close, north of Cairns.

Witnesses have described hearing the zip line snap, seeing the couple hanging before they fell to the forest floor.

Mardi Liebelt was waiting in line behind the couple when the tragedy occurred and says she heard Ms Sanderson screaming.

"The twang when the zip line came back up made an awful noise, then there was just silence for what seemed like forever," she told the ABC.

"And then the lady was just screaming for help, a terrible bloodcurdling scream that I never wish to hear again."

Ms Liebelt said a fellow tourist, a paramedic who was also waiting to use the flying fox, managed to revive Mr Sanderson for a while before he died.

In a statement the family remembered Mr Sanderson as a loving man and thanked emergency services and the hospital for their support.

"We remember Dean as a loving husband, father, son, brother and friend to all," the statement says.

Phoebe Kitto, a director of Jungle Surfing, has offered her deepest sympathy to the families and friends of those affected by the accident.

"It will be thoroughly investigated by Workplace Health and Safety, which will receive our full co-operation," she said.

"We are offering counselling to staff and to our patrons."

In 2004, an English tourist suffered permanent brain damage after plunging 30m on a Jungle Surfing flying fox when she was not properly secured in the harness.

Detectives and Workplace Health and Safety officers will prepare reports for the coroner.

Australian Associated Press