Linnea Mills: The Dive, Lawsuit, PADI Changes, and Documentary

Linnea Mills was an 18-year-old from Missoula, Montana, who drowned on November 1, 2020, during a scuba training dive in Lake McDonald at Glacier National Park. She died from a catastrophic drysuit squeeze after descending overweighted, in borrowed gear that could not be inflated, under an instructor who stayed at the surface. Her family’s $12 million wrongful death lawsuit settled in early 2023, PADI expelled the instructor and later rewrote parts of its drysuit training standards, and no criminal charges have ever been filed.

Who She Was and How She Died

Mills was enrolled in an Advanced Open Water certification course run by Gull Dive Center of Missoula. On the evening of November 1, 2020, the group entered Lake McDonald shortly after 5 p.m., roughly twenty minutes before sunset, for what was supposed to be a dive to about 60 feet. Surface temperature was 49 degrees Fahrenheit. At the depth where Mills was eventually recovered, it was 39. The park had effectively closed for the season, and Gull Dive did not hold a commercial-use authorization to operate there.¹²

Mills had never worn a drysuit before. The one she used was a secondhand purchase, oversized, with an inflator hose whose metric connection did not fit the U.S.-standard fittings on her tank. A drysuit needs air added during descent so it does not compress painfully around the diver and so the diver can control buoyancy. Instructor Debbie Snow knew the hose was disconnected and told Mills to use her buoyancy compensator device instead, essentially treating the drysuit like a wetsuit.³¹

She was also carrying 44 pounds of lead, roughly double what she needed. The weights sat in zippered pockets on her buoyancy compensator and drysuit, nearly impossible to ditch in an emergency. She had no dive light despite the fading daylight. No gear check was performed before the group entered the water.⁴¹

As Mills descended, pressure compressed the suit around her with no way to add air inside it. Her chest constricted. At around 55 to 60 feet she lost her footing on an underwater ledge, and the lead pulled her down. A fellow student, Bob Gentry, wearing a GoPro, reached her on the lakebed at roughly 85 to 94 feet. He later described the suit as having “so constricted…it just squished her.” He could not release her weighted pockets. Her regulator was out of her mouth, so he could not share air. Both sank together before Gentry separated and ascended. Snow stayed at the surface the entire time, occupied with another struggling student, and was unaware anything was wrong below. Mills sank to 127 feet. Her autopsy ruled the cause of death as asphyxia by drowning.¹⁵

The Federal Investigation and the Decision Not to Charge

Because the death occurred on National Park Service land, a Glacier National Park ranger opened the investigation, which the NPS Investigative Services Bureau took over after about eight days. Special agent Jacob Olson led the inquiry. His June 2021 report found that “a number of standard operating procedures for that type of diving were violated,” including use of known faulty equipment and a lack of training for the specific gear. It described Snow as “negligent — and perhaps grossly so — in several respects.”¹

The U.S. Attorney for the District of Montana declined to prosecute. The office acknowledged Snow was “likely at fault to some extent for Mills’ death” but concluded it could not prove criminal culpability beyond a reasonable doubt.⁵

The family’s attorney, David Concannon, has publicly called the investigation flawed. He alleges investigators failed to consult NPS dive safety experts, did not collect data from the divers’ dive computers, did not test Snow for potential mental impairment, and applied an “intentional homicide” standard rather than the lower “negligent homicide” threshold. Mills’ own dive computer went missing and was not submitted as evidence; its data was released only years later.⁵⁶

The Wrongful Death Lawsuit and Settlement

In May 2021, the Mills family filed a $12 million wrongful death suit in Missoula County District Court. The defendants were PADI Worldwide and PADI Americas, Gull Dive Center, owners David and Jeannine Olson, instructor Debbie Snow, volunteer assistant Seth Liston, and Heidi Houck, who had sold Mills the used drysuit without its inflator hose.⁷

PADI’s exposure was the most contested piece. The organization argued its affiliated dive centers and instructors were independent contractors and pointed to disclaimers the students had signed. In December 2022, Missoula County District Judge Leslie Halligan denied PADI’s motion for summary judgment, finding that PADI exercised significant contractual control over how its affiliates operated. The judge wrote that “PADI is in the background of a significant amount of how and why a PADI dive center operates” and that whether this created an agency relationship was a question for a jury.⁸

The suit also alleged PADI knew about problems at Gull Dive before Mills ever enrolled. In June 2019, a diver named Jesse Hubbell had drowned after renting equipment from Gull Dive for a dive at Canyon Ferry Lake; his regulator was later found to have been installed backward. Gull Dive never reported the Hubbell death to PADI, and PADI took no action against the shop. Prospective students like Mills had no way to learn about the prior fatality.²

All parties settled in early 2023 for undisclosed terms rather than go to trial. One report put PADI’s portion in the seven-figure range.⁹⁷

What Happened to the Instructor and the Dive Shop

PADI expelled Debbie Snow on January 19, 2023, around the time of the settlement. Her name appears on PADI’s public list of expelled instructors, and all certifications she issued were canceled.¹⁰⁴ She has not been criminally charged. Concannon has said potential Montana charges could include negligent homicide, reckless endangerment, tampering with evidence, and misleading authorities, and has urged prosecutors to reopen the case.⁹

Gull Dive Center’s owners, David and Jeannine Olson, dissolved the business in 2022 while the lawsuit was pending.⁷

What PADI Changed

After the settlement, PADI announced new drysuit training requirements effective June 1, 2023. Any instructor teaching students who have never used a drysuit during open water dives must now hold a Dry Suit Specialty Instructor certification. PADI also added requirements for certified assistants during drysuit training and modified its drysuit training instructions. Before the change, PADI’s standards had required only “indirect supervision” on a Drysuit Adventure Dive within the Advanced Open Water course.⁴

The Documentary and the Family’s Continuing Push

Missoula filmmaker Damon Ristau produced a 135-minute documentary, How to Kill a Mermaid: The Linnea Mills Story, which premiered at the Big Sky Documentary Film Festival on February 14, 2026, before an audience of roughly 750. The film uses the GoPro footage Bob Gentry recorded during the fatal dive, law enforcement body-camera footage, family home videos, and legal documents not previously public.¹¹⁶

Among the details surfaced in the film: Snow had never dived at Lake McDonald before the training, the group had fewer dive lights than divers, and the dive exceeded the 18-meter maximum depth permitted for the training exercise. A segment follows Linnea’s brother, Nick Mills, as he trains as a diver and returns to Lake McDonald to complete the dive his sister could not. As of early 2026, additional festival screenings were planned and producers were in talks with distributors about a worldwide release.¹¹

Scott Mills, Linnea’s father, has continued to press for a reopened federal investigation. He has submitted evidence to the Department of the Interior’s inspector general and engaged a congressman with oversight authority over the department. He has described the recreational scuba industry as “unregulated and chaotic” and argues that the lack of government oversight of dive instruction contributed to his daughter’s death. He is also writing a book about the case and the industry.¹²⁵

1
Outside Online. The Death of Linnea Mills as Depicted in Upcoming Documentary
2
Missoula Current. Lawsuit Details Negligence in Glacier Diving Death
3
Undercurrent. AOW Trainee Death
4
Undercurrent. Training Death
5
KPAX. Glacier National Park Diving Death Lawsuit Settled
6
The Pulp. Documentary About Linnea Mills Scuba Diving Death in Glacier Premieres
7
Divernet. Mills Death Lawsuit Settled but Will Criminal Case Follow
8
Missoula Current. Judge Says Jury Must Decide PADI Liability in Glacier Drowning Case
9
Undercurrent. Training Deaths
10
PADI. Expelled Instructors
11
Divernet. How to Kill a Mermaid: The Linnea Mills Story
12
Bozeman Daily Chronicle. Harrowing New Film Sheds Light on Missoula Woman’s Scuba Diving Death in Glacier