A scuba dive boat captain has been jailed four years for criminal negligence over a fire that killed 34 people.

Captain Jerry Boylan was also sentenced to three years supervised release by a federal judge in Los Angeles, California.

The blaze on the vessel named Conception in September 2019 was the deadliest maritime disaster in recent American history.

Boylan was found guilty of one count of misconduct or neglect of ship officer last year.

Captain Jerry Boylan. Pic: AP

The charge is a pre-Civil War statute, known colloquially as seaman’s manslaughter, and was designed to hold steamboat captains and crew responsible for maritime disasters.

In a sentencing memo, lawyers for Boylan – who is appealing – wrote: “While the loss of life here is staggering, there can be no dispute that Mr Boylan did not intend for anyone to die.

“Indeed, Mr Boylan lives with significant grief, remorse, and trauma as a result of the deaths of his passengers and crew.”

The Conception was anchored off Santa Cruz Island, 25 miles south of Santa Barbara, when it caught fire before dawn on the final day of a three-day voyage, sinking less than 30 metres from the shore.

Thirty-three passengers and a crew member died, trapped below deck.

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The victims included an environmental scientist, a Singaporean data scientist and a family of three sisters, their father and his wife.

Boylan jumped overboard, and four crew members who followed suit also survived.

FILE - The burned hull of the dive boat Conception is brought to the surface by a salvage team off Santa Cruz Island, Calif., on Sept. 12, 2019. A federal jury on Monday, Nov. 6, 2023, found scuba dive boat captain Jerry Boylan was criminally negligent in the deaths of 34 people killed in a fire aboard the vessel in 2019, the deadliest maritime disaster in recent U.S. history. (Brian van der Brug/Los Angeles Times via AP, File)
The burned hull of the dive boat. Pic: AP

Boylan initially faced 34 counts of seaman’s manslaughter, meaning he could have faced a total of 340 years behind bars.

His lawyers argued the deaths were the result of a single incident and not separate crimes, so prosecutors instead charged Boylan with only one count.

While the criminal case has concluded, there are several ongoing lawsuits.