On September 2, 2019, US Coast Guard Sector Los Angeles/Long Beach received a distress call from the diving vessel Conception, with 39 persons on board.

On the last night of the voyage, the ship was anchored in Platts Harbor off Santa Cruz Island, 21.5 nautical miles south-southwest of Santa Barbara, when it caught fire. Weather conditions were reported as slight to no winds with patchy fog, 2-3 foot seas, and air and water temperature about 65°F. The Conception was carrying 39 persons, 6 of which were crew. Thirty-three passengers and one crewmember died.

Initial interviews of three crewmembers showed that no mechanical or electrical issues were reported. When the fire took place, five crewmembers were asleep in berths behind the wheelhouse, and one crewmember was asleep in the bunkroom. The bunkroom had an emergency escape hatch located on the aft end, which also exited to the salon. There were two, locally-sounding smoke detectors in the overhead of the bunkroom.

A crewmember sleeping in the wheelhouse berths woke up by a noise and got up to investigate. He saw a fire at the aft end of the sun deck, coming from the salon compartment below. The crewmember alerted the crew behind the wheelhouse. As crewmembers awoke, the captain sent a distress message to the US Coast Guard.

The crewmembers attempted to access the salon and passengers below. Not able to use the aft ladder, which was on fire, the crewmembers jumped down to the main deck, one crewmember broke his leg in the process, and attempted to access the salon and galley compartment, which was fully on fire at the aft end and by thick smoke in the forward end, through a forward window. Unable to open the window and overwhelmed by smoke, the crew jumped overboard.

Two crewmembers and the captain swam to the stern, reboarded the ship, opened the hatch to the engine room, and saw no fire. Access to the salon through the aft doors was blocked by fire, so they launched a small skiff and picked up the remaining two crewmembers in the water. They transferred to a recreational vessel anchored nearby, where the Captain continued to radio for help, while two crewmembers returned to the Conception to search for survivors around the burning hull.

Local US Coast Guard and fire departments arrived on scene to put out the fire and perform search and rescue. The vessel burned to the waterline by morning and then sank in about 60 feet of water. Later that day, USCG declared the accident a major marine casualty.

Investigators have collected documents from recent US Coast Guard inspections and visited another Truth Aquatics vessel, Vision, a vessel similar to the Conception. Salvage operations to bring the wreckage to the surface for examination and documentation have also started.

Investigators plan to examine current regulations regarding vessels of this type, year of build, and operation; early-warning and smoke-detection and alarm systems; evacuation routes; training; and current company policies and procedures. Efforts continue to determine the source of the fire.