In his findings, released today, Coroner Richard McElrea confirmed Tayne's death was due to drowning.
The Ministry of Business, Innovation and Employment did not lay any health and safety charges in relation to the accident.
However, Coroner McElrea said the accident highlighted the importance of complying with health and safety codes for surface mining.
There was no embankment on site to prevent Mr Bowes' vehicle from leaving the vehicle track, Coroner McElrea said.
A perimeter embankment was accepted as industry practice.
"An adequately constructed bund of the type health and safety observed on other mine sites would have probably deflected the vehicle or prevented it from leaving the vehicle track. There is no evidence of excessive speed."
The circumstances highlighted the issue of children being taken on to industrial sites, as well as inadequate lighting.
There was no lighting on site on the evening the accident occurred, Coroner McElrea said.
"The only lighting at the scene at the time of the incident was that of the vehicle headlights."
The owner of the mining operation accepted that the installation of spotlights on vehicles would be a worthwhile outcome and "would be reasonably simple" to put in place.
Four days after the incident, Mr Bowes appeared to have trouble with his memory surrounding the event, and an MRI scan showed a malignant intrinsic brain tumour in his right temporal lobe, which has since been treated.
Coroner McElrea said it was possible this may have contributed to the crash.
"It may have affected his ability to work out close distance and space that contributed to the crash."
Coroner McElrea called on Worksafe New Zealand to highlight to the industry the lessons learned from the incident and the need to improve design and policy standards.
"I further recommend that vehicles operating in darkness in such environments be encouraged to have supplementary lamps (spotlights) to assist in lighting of such sites."
Mr Bowes was interviewed by police after the fatal accident but was never charged over the incident.
At the inquest, Mr Bowes questioned why his daughter was left trapped in the air pocket for almost two hours and whether any attempt was made by police and firefighters to see whether Keira or Tayne might have been alive inside the vehicle.
Mr McElrea said that in his assessment of the evidence, and taking into account all the circumstances, the police actions were "entirely appropriate".
- Additional reporting by the Greymouth Star