The co-owner of a Santa Cruz-based diving company is missing after a scuba boat caught on fire early Monday and sunk off the coast of Southern California, leaving at least 25 dead and nine people missing as of Tuesday morning.

Kristy Finstad, 41, is a diving instructor and marine biologist who operates Worldwide Diving Adventures with her husband Dan Chua. She was aboard the Conception when it caught fire early Monday, according to a Facebook post by her brother, Brett Harmeling.

“She’d be the person who could make it if it’s possible. She could hold her breath for an insane amount of time. It just doesn’t sound like there was a chance for anyone to get out,” Harmeling, 31, told the New York Daily News in a phone interview. “She’s done this trip hundreds of times.”

25 BODIES FOUND AFTER CALIFORNIA SCUBA BOAT FIRE, COAST GUARD SAYS

The diving company chartered the 75-foot vessel owned and operated by Truth Aquatics in Santa Barbara for a three-day diving excursion off the Channel Islands, Harmeling said. Finstad’s husband was leading a diving trip off the coast of Costa Rica when the blaze broke out, The Mercury News reported.

The excursion was advertised on Worldwide Diving Adventures’s website as a $665-per-person voyage to get a glimpse at octopi, colorful anemones, crabs, halibut, wolf eels and bioluminescent zooplankton in the waters around the Channel Islands.

There were six crew members and 33 passengers aboard the Conception when it became engulfed in flames early Monday morning. Officials believe the majority of the passengers were asleep below deck in a single room lined with bunk beds when the fire first broke out. A man who’s traveled on the Conception and two other boats owned by Truth Aquatics told The Associated Press coming to the top deck to get off requires navigating a narrow stairway with only one exit.

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As of late Monday evening, the U.S. Guard said 25 bodies were found. Nine others still remain missing, as authorities search through the night. Only five people—all crew members—are known to have survived the fire after they jumped into an inflatable lifeboat and were rescued by a nearby vessel.

Bob and Shirley Hansen--- who own a 60-foot fishing vessel called The Grape Escape—told the New York Times they were asleep when they woke up around 3:30 a.m. Monday to the sound of the five crewmembers pounding the side of their boat desperate to be rescued from their life raft.

"When we looked out, the other boat was totally engulfed in flames, from stem to stern," Bob Hansen said, estimating it was no more than 100 yards from his craft. "I could see the fire coming through holes on the side of the boat. There were these explosions every few beats. You can't prepare yourself for that. It was horrendous.”

The couple said at least some of the men fled the fire in only their underwear. One was crying that his girlfriend was still on board and he was unable to reach her before fleeing. Another said the crew had just helped passengers celebrate three birthdays the previous evening.

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Bob Hansen said two of the crewmembers went back toward the Conception looking for survivors but no one was found. The names of the deceased have not been released. Investigators have not confirmed what caused the fire.

The Associated Press contributed to this report.