negligence in his January death on a dive in the Florida Keys. Famed diver Peter Sotis (right) is among those named in the suit

Stewart, of Toronto, Canada, was diving with Sotis off the coast of Islamorada, Florida when he disappeared in January

The fatal dive took place while Stewart was working on a follow-up film to his 2006 documentary, Sharkwater, which examined the impact of shark hunting

Sotis' company, Add Helium, was also named in the suit, and made the re-breathers used on the dive.

'When you learn more about these defendants and the history of negligent behavior by people like Mr. Sotis, you come to realize this was a preventable tragedy that was going to happen to someone,' Michael Haggard, lawyer for the Stewart family, said in a statement tothe Miami Herald.

Stewart, of Toronto, Canada, was diving with Sotis off the coast of Islamorada, Florida, to film a follow-up to his 2006 documentary Sharkwater, which examined the impact of shark hunting on the ocean's ecosystem.

Sotis and Stewart were investigating the wreck of the Queen of Nassau on January 31 when, the suit claims, they took three dives to the wreck using re-breathers, which extend the length of a dive by scrubbing carbon dioxide from recycled air.

Experts consider that amount of diving with re-breathers pushing the envelope of safety.

The suit claims Stewart and Sotis surfaced together, but said that when Sotis experienced difficulty breathing, Stewart disappeared while dive organizers were focused on treating the other man.

Unspecified damages are being sought by the lawsuit.

A massive manhunt ensued after Stewart