She died from extensive brain injuries after being hit by the propeller.
Boat labourer Tomasi Natutuvuli Tovou was found guilty of manslaughter over the incident in 2009.
Hastings coroner Christopher Devonport today released findings showing Tovou, who did not have a license to operate a vessel, was travelling at speed outside a marked channel where boats were permitted.
He did not employ a "spotter" to warn him of approaching dangers and was bending down to remove a stopper when he struck Ms Stockwell, his findings said.
"Failure to employ safe boating practices resulted in Mrs Stockwell being run over by the boat and hit on the head by the boat's propeller."
Mr Devonport said a pathologist in Fiji who conducted a post-mortem examination on Mrs Stockwell had disposed of her brain before her body was transported back to New Zealand.
Dr Litia Tudravu later told New Zealand police she was embarrassed at Mrs Stockwell's brain not being returned.
Changes had been introduced to ensure better consultation with families over post-mortems and embalming procedures as a result of the case, Dr Tudravu said.
After an investigation into Mrs Stockwell's death, several measures recommended by the Fijian Ministry of Labour were introduced by the Matamanoa resort.
It brought in more staff training around dealing with such accidents, improved boating qualifications and undertaking seas safety courses, first aid training and propeller guards installed on larger engines.
After an investigation into Mrs Stockwell's death, several changes recommended by the Fijian Ministry of Labour recommended were introduced by the resort including more staff training around dealing with such accidents, improved boating qualifications and undertaking seas safety courses, first aid training and propeller guards installed on larger engines.
The newlywed and her husband arrived on the island for their honeymoon days earlier after their wedding in Blenheim.
On the morning of November 30, the couple picked up masks, goggles and fins from the resort shop to preparation to go snorkelling.
The man serving them helped fit the gear but did not tell them where around the island they should avoid snorkelling, the Coroner found.
They entered the water at 10.30am in front of their accommodation. Mr Stockwell was wearing green board shorts, fins, mask and snorkel, his wife a black bikini, green mask and snorkel.
The pair were swimming on top of the water , parallel with the beach, 10-15m from the shore, when Mrs Stockwell indicated she was going to stop to take a photo.
"I just slowly carried on swimming and then I heard a noise so I lifted my head and saw the boat. It was a drone noise, it was probably the engine but I didn't hear it until it was too late,'' Mr Stockwell is reported as saying.
The boat was coming at him from behind, travelling in the same direction as the couple were. At that moment he couldn't see his wife, and kicked out of the way of the boat, which "Missed me by less than a metre'', he said.
As the boat passed, he heard a bang, and it stopped. Then, "everything happened so fast''.
"Initially I couldn't see Becky, she had been knocked under the water and then I saw blood on top of the water and then she came to the surface face down.
"I grabbed her and lifted her head out of the water, and I started screaming for help. I noticed she was bleeding from the head. the snorkel and mask were gone.''
Matamanoa resort did not have an oxygen mask available at the time of Mrs Stockwell's death, Mr Devonport found.
However, her injuries were so severe they would not have been survivable, he said.
