SANTA BARBARA, Calif. -- Thirty-three people signed up to spend what promised to be a glorious Labor Day weekend aboard the Conception, a 75-foot boat that offered a scuba diver's dream: unlimited diving among colorful underwater sea life, with gourmet meals served between dives.
But on the last part of the three-day trip, the ship caught fire Monday off California's Santa Cruz Island. At least 20 people died, Santa Barbara County Sheriff Bill Brown said.
"This is probably the worst-case scenario you can possibly have," Brown said. "You have a vessel that's on the open sea, that is in the middle of the night. I mean, it's 3:30 in the morning."
Of the 39 people on board -- 33 passengers and six crew -- only five people have been found alive. The five survivors are all crew members.
In a news conference Tuesday morning, officials said 20 bodies had been recovered. Divers had spotted another four to six victims during their search, but the boat would need to be stabilized before they could be retrieved, authorities added.
The Coast Guard announced they would be calling off their search and rescue efforts. Officials said all those still unaccounted for were feared dead and that the effort would transition to a "recovery mission."
Watch the full news conference here:
Victims were likely asleep
Questions abound over why the boat caught fire, and whether lives could have been saved.
A mayday call reveals the tension between a Coast Guard dispatcher and the Conception's captain. But only the dispatcher's words could be heard.
The captain apparently reports a fire and provides a location. The dispatcher is heard saying, "And there's 33 people on board the vessel that's on fire, they can't get off? ... Roger, are they locked inside the boat? ... Roger, can you get back on board and unlock the boat, unlock the door so they can get off? ... Roger, you don't have any firefighting gear at all? No fire extinguishers or anything?"
Later in the conversation, the dispatcher asks, "Was that all the crew that jumped off? ... Roger, is the vessel fully engulfed right now ... Roger, and there's no escape hatch for any of the people on board?"
At one point, the caller says, "I can't breathe."
Ventura County firefighters were able to reach the boat within 15 minutes, the fire department said.
But by then, it was engulfed in flames.
Firefighters struggled to extinguish the fire because each time it was snuffed out, flames flared back up -- perhaps because of the fuel on board, the Coast Guard's Aaron Bemis said.
By 7:20 a.m., the ship began to sink in 64 feet of water. The boat had burned down to the water line, Santa Barbara County fire spokesman Mike Eliason said.
Many of the passengers were below deck, most likely sound asleep when the fire broke out, authorities said.
None of the people who were on board have been identified.
The company that operates the Conception, Truth Aquatics, declined to comment to CNN.
A local captain responds to the mayday call
Capt. Paul Amaral, owner of maritime towing company TowBoatUS Ventura, heard the mayday call from the mainland California city of Ventura. He jumped into his 27-foot boat and started the 30-mile trip to Santa Cruz Island.
"Once I got on scene there was only one fire boat trying to put out the fire," Amaral said Tuesday.
"I proceeded to do a coastline search for passengers, and once I didn't find anyone, I offered assistance on fire fighting."
At one point, the Conception broke free from its anchor and started drifting toward the island -- meaning larger firefighting boats couldn't go any closer.
So Amaral had to step in, "I was in a much smaller 27-foot boat and was able to go in close to the boat, attach a chain and pull it away from the island," he said.
After the boat sank, Amaral said several bodies surfaced. He said he helped with the recovery efforts.
"I have responded to several boat fires, but to know these people were trapped on that boat, it's horrific," he said.