And a diver photographing her spouse inadvertently captured a photo of Tina Watson lying lifeless on the sea floor.
Nearly five years after the incident, an inquest was launched into her death and Watson was charged with his wife's murder. He returned to Australia and pleaded guilty to negligent manslaughter, essentially admitting that he failed to save his wife, but he did not kill her.
He served 18 months in an Australian prison. In November 2010, Australia returned Watson to Alabama after the state agreed to not seek the death penalty. Instead, Watson faces the possibility of life in prison.
When Watson was freed from Australia and returned to Alabama, then-Attorney General Troy King was up for re-election. King staged a national media campaign arguing that Watson is a killer who should pay for the death of his wife. But King lost the election and is no longer in public office.
Now 40 year veteran prosecutor Valeska heads the case. He is a man who has prosecuted 10 men to their execution, more than any serving prosecutor in Alabama.
Watson, who was freed on bond in 2010, lives with his new wife of four years, Kimberly Lewis, and works with his father, David Watson.
During Watson's Alabama trial, over a dozen Australian witnesses are expected to testify.
The defense says one of their witnesses will explain that, based on the data from Tina Watson's air tank, it is impossible that Watson turned off her air.
The dive company that managed the couple's sea excursion, Mike Ball Expeditions, took some blame for her death. They pleaded guilty to contravening their own safety standards and were fined $6,500.
Diving can be a dangerous sport, the defense notes. In 2008, there were 40 deaths in Florida, the most popular diving destination in the United States.
"Gabe's dive expertise has been blown out of proportion. This was Tina's first open water dive, and Mike Ball Expeditions took her on one of the most difficult dives, knowing her lack of experience," Bloomston says.
Bloomston adds that Watson, who has been painted by the prosecution as unemotional, still struggles emotionally today.
"After Tina's death, he attended grief counseling and met with a young widowers group. He could not date or act socially. He was numb."