Watson, with good behaviour, will be a free man within 12 months.
"It makes me sick, he should get 40 years for sure! Loser!" a reader vented on Alabama's Birmingham News website on Friday.
Another wrote: "One year. That is pathetic. I hope that when he does get out and returns home everyone gives him hell."
Tina's friends and relatives also used the Birmingham News website to show their anger.
"I am one of Tina's cousins and we are completely and totally outraged by this sentence ... what a complete slap in the face to Tina's family," the cousin wrote.
Watson made a surprise deal with Queensland prosecutors, agreeing to plead guilty to the manslaughter of his 26-year-old wife.
Prosecutors did not pursue a murder charge.
Tina died on October 22, 2003, while scuba diving with her husband of just 11 days on Queensland's Great Barrier Reef. The couple married in Alabama and chose Australia as their honeymoon destination.
Watson, 32, a certified rescue diver, said he panicked when his wife got into trouble during the dive.
Prosecutors told Queensland's Supreme Court Watson "virtually extinguished any chance" of Tina's survival when he allowed her to sink to the ocean floor without making any serious attempt to retrieve her, inflate her buoyancy vest or remove weights from her belt.
Another diver told a Queensland coronial inquest last year Watson engaged in an underwater "bearhug" with his wife.
Tina's death received widespread publicity in the US, with NBC's investigative news program, Dateline, profiling the case and Tina's grieving parents appearing on numerous other news shows.
The case drew comparisons to the 2002 death of Laci Peterson, a pregnant 27-year-old Californian woman whose husband, Scott Peterson, was found guilty for her murder and sentenced to death.
"Somewhere Scott Peterson is green with envy!" a Birmingham News reader commented.
Another warned Americans the US judicial system will follow Australia's perceived lenient system under new president Barack Obama.
"Get ready for the Australian Judicial System, it's coming to America under Obama," a reader submitted.
"Australia has outlawed firearms, and disarmed law abiding citizens. Crime has skyrocketed. (I'm SHOCKED!) Of course the criminals still have and use guns ... Australia has legalised prostitution, and even put out ads and paid prostitutes to come to Australia for the Olympics!"
While most readers were furious about Watson's sentence, others joked Australia seemed like a place to go for Americans who want to do away with their wives.
"I'm booking a vacation to Australia right now for me and the ol' lady," a reader wrote.
6 Jun 2009
Anglo Masonic Justice at it's BEST.
Proves that under the right circumstances, you can murder someone, AND get away with it.