The five survivors, including the boat's captain and four crew members, were above deck when the blaze broke out at 3:15 am
Federal safety investigators on Tuesday promised an exhaustive probe into the fire that killed 34 people on a dive boat as many of the charred bodies remained trapped in the sunken wreckage off the California coast or missing in the ocean.
After recovering the remains of 20 people from the 75-foot (23-metre) Conception or from the waters where the dive ship sank off Santa Cruz Island, officials said they believed none of the 14 victims initially classified as missing had survived the fast-moving flames.
"There were several other victims that were seen by the divers - between four and six - that are still between the wreckage, but due to the position of the boat they were unable to be recovered before nightfall," Santa Barbara County Sheriff Bill Brown told reporters.
"Today, efforts will be made to stabilize the boat so that divers can safely enter it, search it and recover additional victims," he said.
The five survivors, including the boat's captain and four crew members, were above deck when the blaze broke out at about 3:15 am Pacific time and escaped in an inflatable boat. A crew member who perished was apparently sleeping below deck with the passengers at the time.
National Transportation Safety Board member Jennifer Homendy said 16 investigators were already assigned to the probe, including specialists in operations, engineering, survival factors and fire analysis.
The investigators will collect all perishable evidence while on scene for at least a week, she said, but the Conception would remain on the ocean floor, more than 60 feet below the surface, until a site survey had been completed.
A few scant details about the victims, who ranged in age from 17 to 60, began to emerge as emergency workers planned to use DNA analysis to identify the remains of the 20 bodies recovered so far. Most of the victims were from the Santa Cruz and San Jose area, authorities said.
"Mayday, Mayday, Mayday"
A memorial to the victims grew alongside a dock not far from where the ship was usually docked in Santa Barbara as members of the close-knit boating community reeling from the tragedy wove flowers into a wood and wire fence and constructed a makeshift memorial https://www.reuters.com/article/us-california-fire-memorial/we-all-have-... with flowers and candles.
"It’s just such a horrific notion to think what the people down in the below decks, the people sleeping down there must have gone through," said Judy Weisman, 72. "How terrifying."
An audio recording of a desperate call made to the US Coast Guard as flames engulfed the boat offered a glimpse into that terror as a man could be heard pleading for help.
"Mayday, mayday, mayday!" he said in the garbled recording of the call.
"That's a distress, this is the Coast Guard Sector Los Angeles on channel 1-6, what is your position ... and number of persons on board? Over," the dispatcher answered.
"Twenty-nine. Twenty-nine POB," said the man, using the abbreviation for "people on board" a vessel. "I can't breathe! ... Twenty-nine POB."
The dispatcher requested the GPS location of the vessel at least two more times but the caller apparently failed to respond.
Marine biologist Kristy Finstad, 41, was leading the dive trip on the Conception, according to her brother, Brett Harmeling. Finstad co-owned Worldwide Diving Adventures, which had chartered the boat for a three-day excursion to the Channel Islands.
"No final word on my sister Kristy; however it is likely she has transitioned to be with the good lord," Harmeling said in a Facebook post on Tuesday.
A sea shell inscribed with the name "Kristy" was hung on the wooden fence at the dock.