Exactly a week ago my phone started pinging late at night. I was getting messages from too many people who I deem a credible source, of the tragic news that Jared Hires had died at Plura Cave.

I got the news confirmed. Cried. Then opened up my laptop and wrote an article announcing Jared Hire's death. At present over 45,000 of you have read it. 

Almost immediately Facebook lit up with some exceptionally fine tributes, to be quickly followed by the inevitable speculation. I had reported that Jared Hires actively seized underwater and a cave diver had performed a rescue, swimming him out of Plura, whilst the other diver went ahead to alert topside and the emergency services.

Any one know what happened? What cause that actively seizure? He had any health issue or illness? Post on Facebook

The above is a typical post made on social media within hours of Jared Hires dying. It's little wonder that dive educator and author Steve Lewis posted two days ago "I am dismayed to read so much armchair quarterback nonsense speculating on the cause of death for our dear buddy Jared Hires. 

While it is human nature to be curious and seek answers, please just chill.

Jared was a popular figure in our industry, and had, because of the sharing nature of his whole family, lived his life in the spotlight, so it's understandable that we want to know what took him from us. But those of us who have been on the blunt-end of tragedy know how difficult it is to deal with speculation about the passing of someone we loved... still love.

Out of respect for Jared's family, his friends (especially those who were part of this faithful expedition), and the rest of a concerned and shocked community, keep any and all of this stuff private. Please. Empathy at this time is way more important than anything else."

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An Exceptional Family

Thanks to the generosity in thinking by the Hires Family there are now some answers from DAN. Prior to writing this, I had a conversation with a spokesman for the Hires Family earlier tonight. The family have drawn great strength from this report and it has comforted them.  

DAN's preliminary accident analysis and the results are released today; Wednesday 10 April 2024. 

"The basis of this preliminary analysis (April 9, 2024) includes an interview of one of the diver’s dive partners, who witnessed the event, conversations with the diver’s father after the event, and the downloads of the CCR controllers of all three divers on the dive."

The Dive

"A team of three experienced rebreather divers planned to execute a check-up dive in preparation for a deeper dive the following day to confirm that all gear was in working order after travel. All three divers used adequate equipment that they were familiar with and wore adequate thermal protection for the dive. It was their first dive in Plura on this trip, however, Diver 1 and 3 had dived the system in previous years. 

Diver 1 (witness) took the lead, followed by Diver 2, and Diver 3 (Jared Hires) in the back. The first half of the dive was uneventful with a maximum depth of 34 m / 110 ft, all three divers surfaced after 30 minutes in the air-filled 'Wedding Chamber'. 

The dive was planned as a circuit, but the Wedding Chamber did mark the approximate half-time point of the dive. The team briefly discussed and confirmed that all equipment was in working order and everyone was feeling well and descended again after two minutes at the surface in the same formation with Diver 1 in the lead and Diver 3 (Jared Hires) in the back. 

The CCR controllers logged this as a separate dive. Consulting the logs provided by the team, the descent for this second dive was also uneventful for all three divers until minute 16, when Diver 3’s (Jared Hires) log shows a sudden descent from 25 m / 82 ft to 29 m / 95 ft in less than 20 seconds. 

At this point, Diver 1 had turned around to assist Diver 2 deploying a backup light after their primary light had failed. While reconfiguring their formation to put Diver 2 in the lead, Diver 1 witnessed Diver 3’s (Jared Hires) light moving erratically and recalls hearing Diver 3 (Jared Hires) screaming, potentially trying to articulate a problem. 

When Diver 1 reached Diver 3 (Jared Hires), he was already in full tonic-clonic convulsions. His loop was not in his mouth but was found to have been closed, which suggests that Diver 3 (Jared Hires) had attempted to bail out but was not able to get his bailout regulator into his mouth in time before the onset of his seizures. 

After unsuccessful attempts by Diver 1 to secure Diver 3’s (Jared Hires) airway, he proceeded to swim the still convulsing diver towards the exit, a distance of roughly 250 m (800+ ft) with several depth changes. When Diver 3 (Jared Hires) had stopped seizing after approximately 3 minutes, Diver 1 tried to insert a regulator into his mouth again but could not unclench Diver 3’s (Jared Hires) jaw, so he proceeded to swim him out of the cave. 

He signalled Diver 2 to swim ahead and to alert the surface and call for assistance. A diver at the surface was able to meet them close to the exit and assist in bringing Diver 3 (Jared Hires) to the surface. Diver 1 and 3 surfaced after 31 minutes (17 minutes after onset of convulsions).

CPR was initiated immediately, and oxygen and AED were ready within minutes after surfacing and used before and in conjunction with local EMS response via ambulance and helicopter. Unfortunately, all resuscitation efforts by the team at the surface and EMS for   almost 2 hours remained unsuccessful.

Medical History

After communication with the deceased diver’s family, it has come to light that Jared Hires had an unprovoked seizure for the first time the previous year and that there is a family history of very rare and to this date medically unexplained seizures, in these cases connected with overexertion, stress, and dehydration.

This report has given the Hires family great comfort. They have learned why Jared died, and wish to share it with the community. Rosemary E Lunn

Diver Well!

Outside of the recreational and technical diving industry, Dive Supervisors around the world verbally confirm with the diver (before diving operations commence) that the diver wants to dive and that they are well. 

Jared Hires told his diving team on Wednesday 3 April 2024 that he had slept well, was not jetlagged, and was feeling rested that day. It must be mentioned however, that the week before the trip to Norway, the diver had displayed symptoms of a viral infection with flu-like symptoms and gastrointestinal involvement, which may have added to potentially existing electrolyte imbalance and dehydration from intercontinental air travel.

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Seizure not due to oxygen toxicity

A word about oxygen toxicity and why this was most likely not oxygen toxicity:

When reading about seizures in diving, a logical first conclusion people jump to is central nervous system oxygen toxicity which presents in symptoms just as the ones described above. Plenty of literature is available on the topic and training courses as early as open water or at the very latest Enriched Air Nitrox courses cover the topic. Rebreather divers are painfully aware of the three “H”s, Hyperoxia, Hypoxia, and Hypercapnia, which each can lead to disabling injury and death/drowning while diving.

The review of the logs of this dive does not support the theory of an oxygen-induced seizure. At no point before the event did oxygen levels or cell readings spike significantly. 

The ppO₂ very briefly (less than 1 minute) exceeded the high setpoint (set to 1.2) to 1.3. Changes in ppO₂ are only seen after the event and are easily explained by the solenoid still firing and the efforts of Diver 1 to vent and inflate equipment to exit the cave.

The narrative suggests that Diver 3 (Jared Hires) seems to have felt the onset of a seizure, which makes an underlying medical condition more likely than an oxygen-induced seizure. 

These seizures rarely present with an aura or warning signs. A medical event is also more consistent with the duration and quality of the witnessed seizure, which would best be described as a Grand Mal rather than oxygen toxicity.

Unprovoked seizures can develop suddenly and at any age. The risk of recurrence of a seizure after an individual has experienced a single unprovoked seizure has been published in a comprehensive literature review in 2023 and it states that the likelihood of seizure recurrence is between 25% and 41% in the first 6 months to 2 years.

Summary

After careful review and consultation with experts in diving accident analysis, DAN concludes that this tragic accident was caused by a medical event and predisposition of the diver, and that neither equipment failure or error in human-machine interaction is responsible for the outcome. 

This was an incident whilst diving. NOT a diving incident

The diver was likely not aware of the implications that a first-time unprovoked seizure could have. The dive team did everything humanly possible in this challenging environment to rescue the diver.

In summary, DAN feels that it is important to educate the diving community about medical and physiological issues that, while easily manageable at the surface, can prove fatal when experienced underwater, especially in extreme environments.

Honouring Jared Michael Hires

The Hires family has requested that divers who wish to honour and remember Jared are most welcome to make donations to the North Florida Springs Alliance and state it is in the memory of Jared Hires.