Another death during Navy SEALs 'Hell Week' highlights the dangers in one of the military's hardest selection courses

• A Navy SEAL candidate died after completing the selection course's "Hell Week" in early February.
• The Navy has procedures for medical emergencies, but deaths during SEAL training are not unheard of.

On February 4, US Navy Seaman Kyle Mullen died after completing "Hell Week," a notoriously difficult part of the training for US Navy SEAL candidates. Another candidate was hospitalized on the same day.

In a press release, Naval Special Warfare Command said that Mullen and his Basic Underwater Demolition/SEAL (BUD/S) classmates successfully completed Hell Week earlier that day and that he "was not actively training at the time of his death."

The command said that Mullen's cause of death was unknown and an investigation was underway. The unfortunate event again highlights the inherent dangers of special operations, where the risk of death or serious injury is present both on the battlefield and in training.

Death in Hell Week

Hell Week is probably the most well-known part of any special-operations training regime in the world.

The six-day ordeal, beginning on Sunday evening and ending Friday morning, usually takes place at the end of first phase of BUD/S. During this period, students' physical and mental endurance is rigorously tested with runs totaling over 200 miles, hours of physical training, and swims in the frigid waters of the Pacific.

During all BUD/S evolutions, there is an ambulance on standby near the students in the event of a medical emergency. Navy SEAL corpsmen are ready to provide medical assistance if needed. Instructors and staff work together closely and students go through a medical check every day during Hell Week.

"All instructors are thoroughly educated in risk and injury prevention during Hell Week. There are medical personnel present 24 hours a day and doctors conduct regular full-body checks periodically to evaluate for pneumonia, cuts that are infected, and signs of disease," Bob Adams, a retired Navy SEAL officer and doctor, told Insider.

Following 12 years in the SEAL Teams, Adams went to medical school and became an Army doctor and eventually the command surgeon of the Army's elite Delta Force. Adam's details the incredible pressures that Hell Week puts on the body in his 2017 book, "Six Days of Impossible: Navy SEAL Hell Week — A Doctor Looks Back."

Hell Week can have lasting effects on those who go through it, Adams said.

"Of greatest interest to me as a doctor looking back — our core body temperatures at times dropped below 90 degrees (98.6 is normal), and now many years later, all of us have core body temperatures below normal," Adams added. "This matters because our brain (the hypothalamus) was permanently reset to a lower 'normal,' and when exercising or even sleeping, our sweating is greater than others as the body tries to cool itself to the new set point."

Navy SEAL students are geared to overcome adversity and push through, often against odds and reason.

"It is in the BUD/S mentality to 'suck up the pain' and move on with your job. Students are encouraged, and often forced by the realities of the training regime, to hide or deal with injuries while in training," a former Navy SEAL officer told Insider.

Those were not "life-threatening injuries," the former officer said, "but pneumonia, broken legs, ankles, hands, what have you, are happening, and the training is not stopping because of them, so students who do not want to get rolled back and repeat the training have to push through."

A dangerous profession

The risks don't end with Hell Week. In the second phase of training, students spend most of their time in the pool learning the basics of combat diving.

It's a stressful time. The "pool competence" event at the end of second phase typically forces several students in each class to start over or drop out. Shallow-water blackouts are common throughout second phase. In the third phase, students get to handle live ammunition and explosives while sleep-deprived.

"You'll be colder, hungrier, and more tired in the [SEAL] Teams than in BUD/S — way more," a former enlisted Navy SEAL told Insider.

"Students will hear that a lot during training but you don't really believe it — how can you fathom being colder when you've just spent 10 minutes in the freezing Pacific in the middle of the night and you have to literally pie yourself to get a little warm? But it's true and accurate. Life in the [SEAL] Teams sucks way more than BUD/S," the former enlisted SEAL said.

This is the second fatal training incident for the Naval Special Warfare community in four months. In November, Cmdr. Brian Bourgeois, commanding officer of SEAL Team 8, died of injuries he suffered during a nighttime fast-rope exercise in Virginia Beach.

For the Navy SEAL community, training deaths aren't common, but they aren't rare.

"At the end of the day, it is a dangerous profession. Training for it is dangerous and doing it is dangerous, and they are dangerous because the demands and mission-sets are high," the former SEAL officer said.

SEALs are the dedicated maritime component for US Special Operations Command and are the ones called on when there's a maritime contingency, the officer added. "There is no room for error or failure downrange. So the training must be hard."

Stavros Atlamazoglou is a defense journalist specializing in special operations, a Hellenic Army veteran (national service with the 575th Marine Battalion and Army HQ), and a Johns Hopkins University graduate.