The Tragic Loss of Linnea Mills: Investigating Safety Failures and the Push for Reform in the Scuba Diving Industry

As the winter sun dipped behind the jagged, snow-dusted peaks of the Rocky Mountains in Glacier National Park, the surface of Lake McDonald remained deceptively calm, a glass-clear mirror reflecting the fading light of November 1, 2020. At approximately 5:00 PM, 18-year-old Linnea Mills waded into the frigid waters, embarking on what was intended to be a routine training session for her Advanced Open Water and drysuit certifications. The air was crisp, the shoreline was hushed, and the water temperature hovered at a bone-chilling 49 degrees Fahrenheit. Within sixty minutes, a series of catastrophic equipment failures and alleged procedural oversights would transform this educational exercise into a fatal tragedy, leaving Linnea trapped at the bottom of the lake. Her death has since ignited a firestorm of controversy regarding the safety protocols of the scuba diving industry, the lack of federal oversight in recreational diving, and the harrowing reality of what happens when technical training is rushed in extreme environments.

Linnea Mills was a daughter of Montana, named after the delicate, bell-shaped Linnaea borealis flower that carpets the forest floors of the Treasure State. A graduate of Hellgate High School in Missoula, she was known for her adventurous spirit and a deep-seated love for the natural world. Her interest in diving had been sparked years earlier, having explored the vibrant ecosystems of the Great Barrier Reef in 2018. However, the transition from the tropical, buoyant waters of Australia to the high-altitude, cold-water environment of the Northern Rockies required a significant leap in technical skill—specifically the mastery of a drysuit. Unlike a standard wetsuit, which allows a thin layer of water to enter and be warmed by body heat, a drysuit is a complex piece of equipment that keeps the diver completely dry by sealing out water and utilizing a layer of air for insulation. This air layer, however, creates significant buoyancy challenges, necessitating the use of an inflator hose connected to the diver’s air tank and an exhaust valve to manage the volume of air within the suit as pressure changes during descent and ascent.

The National Park Service (NPS) investigation into the incident, led by Special Agent Jacob Olson, revealed a "cascading accident" fueled by what the report characterized as a blatant disregard for standard operating procedures. According to the investigation, Linnea had never worn a drysuit prior to the day of her death. Industry standards typically dictate that a student’s first experience with a drysuit should occur in a controlled environment, such as a swimming pool, to practice buoyancy control and emergency drills. Instead, Linnea was led directly into the deep, dark waters of Lake McDonald just as night was falling. The technical failures began before she even submerged. Investigators discovered that the drysuit provided to Linnea was significantly oversized, and the inflator hose—a critical component for maintaining buoyancy and preventing the suit from collapsing under water pressure—reportedly did not fit the suit’s intake valve. Legal representatives for the Mills family alleged that the hose utilized a metric fitting while the suit was equipped with U.S. standard hardware, making a secure connection impossible.

Perhaps the most egregious error identified in the NPS report was the amount of weight Linnea was instructed to carry. To counteract the natural buoyancy of a drysuit, divers wear lead weights. While an experienced diver of Linnea’s stature would typically require approximately 22 pounds of weight for such a dive, she was outfitted with a staggering 44 pounds. These weights were not placed on a quick-release belt, which is the standard safety configuration for emergency shedding; instead, they were zippered into the pockets of her buoyancy control device (BCD), making them nearly impossible to discard in a moment of crisis. This "over-weighting" created a situation where Linnea was essentially an anchor. Once she began to descend, the water pressure began to compress the air inside her suit—a phenomenon known as "suit squeeze." Without a functioning inflator hose to add air to the suit, the fabric began to crush against her body with immense force, restricting her movement and her ability to breathe.

The dive plan was modest: a ten-minute descent to no more than 60 feet. However, Lake McDonald’s geography is unforgiving. While a shallow shelf hugs the shoreline, the lakebed eventually drops precipitously into a "bathtub" shape, reaching depths of nearly 500 feet. Footage captured by the head-mounted camera of fellow student Bob Gentry provided a haunting record of Linnea’s final moments. At a depth of roughly 45 feet, Linnea began to show signs of distress, making "feeble, reaching gestures" toward her instructor. By 55 feet, she was standing on an underwater ledge, signaling for help once more. Moments later, the weight of the lead and the constriction of the suit caused her to lose her footing. She slid off the ledge and vanished into the darkness of the deeper water. Gentry attempted to follow her, eventually finding her on the lakebed at 94 feet. Her regulator—the mouthpiece providing her air—had been pulled from her mouth. Gentry attempted "buddy breathing," a desperate maneuver where two divers share a single air source, but the suit squeeze was so severe that Linnea’s chest could not expand to take in the air. Trapped under 44 pounds of lead and the crushing pressure of the depths, she was immovable. Gentry, nearly out of air himself, was forced to surface to seek help.

The recovery of Linnea’s body took another 20 minutes. When the instructor and another student finally brought her to the surface from a depth of 127 feet, the water temperature was a lethal 39 degrees. Despite prolonged efforts to perform CPR on the shoreline, Linnea was unresponsive. The official coroner’s report later ruled the cause of death as asphyxia by drowning. The tragedy was exacerbated by the remote nature of Glacier National Park in the winter; with limited cell service and the park’s main arteries closed for the season, emergency medical services were over an hour away. The investigation concluded that the dive should never have proceeded under those conditions with an untrained student using faulty, mismatched equipment.

In the years following the accident, the Mills family has sought accountability through both the civil and criminal justice systems. While a lawsuit against the dive shop and those involved was settled in 2023, the quest for criminal charges has been met with frustration. In June 2021, the NPS Investigative Services Bureau issued a report stating that the instructor was "negligent—and perhaps grossly so," yet federal prosecutors declined to move forward with a criminal case, citing the difficulty of proving "beyond a reasonable doubt" that the negligence rose to the level of criminal culpability. This decision has sparked a broader debate about the regulation of the scuba diving industry. Unlike aviation or commercial shipping, recreational scuba diving is largely self-regulated by organizations like the Professional Association of Diving Instructors (PADI). While these organizations set rigorous standards, they lack the legal authority to enforce them or to shutter businesses that fail to comply.

The documentary How to Kill a Mermaid: The Linnea Mills Story, directed by Damon Ristau, seeks to bring these systemic issues to light. By utilizing law enforcement body-camera footage and the primary source video from the fatal dive, the film paints a harrowing picture of a preventable tragedy. It also connects Linnea’s death to other incidents involving the same dive shop and the broader industry. In 2019, 40-year-old Jesse Hubbell died during a dive at Canyon Ferry Reservoir while using equipment rented from the same shop Linnea used. More recently, in 2025, 12-year-old Dylan Harrison died during a certification class in North Texas, an incident that her family also attributes to systemic safety failures and a lack of instructor oversight. These recurring tragedies suggest that Linnea’s death was not an isolated "accident" but rather a symptom of an industry where the pressure to process certifications quickly can sometimes supersede the fundamental duty of care.

For the Mills family, the pain of Linnea’s absence is coupled with a determination to ensure her story saves others. Her brother, Nick Mills, has turned his grief into a mission. Now a certified divemaster, Nick frequently dives in the very waters where his sister lost her life, viewing the sport as a way to maintain a connection to her adventurous spirit. He also heads The Linnea Foundation, a non-profit dedicated to the social and environmental causes Linnea championed. "I understand now why she was so passionate about diving," Nick said in a recent interview, "but I also see how easily these tragedies can be avoided with proper respect for the equipment and the environment."

The story of Linnea Mills serves as a somber reminder of the inherent risks of technical outdoor pursuits and the critical importance of instructor accountability. As her father, Scott Mills, continues to push for federal authorities to reconsider the case, he remains focused on the legacy of his daughter—a young woman whose life was cut short by a series of avoidable errors in a place she found beautiful. The documentary, which premiered at the Big Sky Film Festival in 2025, stands as both a memorial to Linnea and a call to action for an industry that must reconcile its pursuit of profit with the absolute necessity of diver safety. In the silent depths of Lake McDonald, the lessons of November 1, 2020, remain etched in the memory of a community and a family that refuses to let her death be in vain.