Shortly before the fatal dive, Lex Warner, 50, suffered severe lacerations to his liver after falling over on the deck of a chartered diving vessel.
His widow, Deborah, 42, is now planning to sue the diving company, claiming her husband was allowed to get into the water despite suffering those serious injuries.
Six weeks after his death, Mrs Warner suffered a miscarriage, triggered by the stress of losing her husband.
The inquest heard he died after jumping into the water on 14 August, 2012, minutes after being given the all-clear by skipper Andrew Cuthbertson. He began to suffer serious difficulties after diving to 88 metres and, despite being hauled to the surface, was pronounced dead.
His widow, who is bringing up their son, Vincent, who was nine months old when his father died, has vowed to sue Scapa Flow Charters, who ran the diving company, accusing them of negligence.
She told the inquest she had found out she was ten weeks pregnant while Mr Warner was on the boat, so called to tell him. She said he was delighted.
“He told me a dive planned that morning had been cancelled because of bad weather conditions,” she said. “He was still upbeat but was also excited about coming home. That was the last time I spoke to him.
“I was actually told by police that Lex had drowned because no-one knew about the fall at that time. It was only when I went to Scotland for the post-mortem that I found out he had sustained injuries not consistent with diving.
“There have been two other deaths of divers using these boats since 2007.”
She added: “Lex was a real joker, but he was very serious about his diving. He would never have jeopardised his safety.
“Since the day it happened, I’ve not cried because I need to know exactly what happened before I can have any sort of closure. I believe the organisers of the dive did not carry out the proper checks on Lex after he fell. They let him carry on the dive when he was clearly badly injured.
“I do not believe justice has been served for Lex and I want to avoid this kind of avoidable tragedy happening again.”
Mr Warner, a building company director from Sutton Coldfield in the West Midlands, was on board the Jean Elaine when he slipped on deck and suffered the liver injuries.
He then dived to 88 metres but began to feel unwell and launched a desperate bid to return to the surface.
But by the time he was hauled out of the water by Mr Cuthbertson, he had stopped breathing and attempts to resuscitate him failed.
At the inquest in Birmingham, Captain Gavin Pritchard, an inspector for the Marine Accidents Investigation Branch, said Mr Warner’s diving group had not been warned of the dangers of walking on deck in full diving gear.
“There was no evidence of a formal risk assessment of a fully-dressed diver moving from the seated position to the point of entry into the water.
“It was our recommendation to conduct a thorough review of the safety arrangements to minimise risk to divers as they prepare to enter the water.”
He added: “The severity of the injuries was such that if he had not dived, his condition would have still reached serious medical emergency level.”
Coroner Louise Hunt recorded a verdict of accidental death.