It was mid-morning on April 15, 2017, when Xisco Grácia and Guillem Mascaró parked their car and started gathering up supplies. Xisco, like many of us, spent every week looking forward to Saturdays. Rarely did a weekend go by without Xisco indulging in his passion. A respected 54-year-old geology teacher, Xisco had devoted most of his life to collecting and studying rocks, but it was how he did those things that gave him purpose. Xisco was a cave diver and today’s mission would take Xisco and Guillem into portions of a cave that had never been explored before. In addition to gathering rock samples, Xisco loved to measure and map caves. An explorer at heart, Xisco was driven by discovery. He loved the idea of being the first human to lay eyes on a cave’s closely-guarded secrets.

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He was certainly in the right place for it. Xisco was a resident of Mallorca, the largest of four Spanish-owned islands in the Mediterranean, situated approximately 200 kilometers to the east of mainland Spain. A popular holiday spot for vacationing Europeans, tourists began flocking to Mallorca in the 1950s to enjoy its 50 kilometers of white-sand beaches, dry summers, and luxurious resorts. It’s also home to more than 200 cave systems and the full Mallorca experience for tourists includes seeing at least one. Vacationers tended to visit caves that had been outfitted with lights, railings, walkways, and even gift shops, but for those with a taste for adventure, Mallorca offered plenty of caves without man-made amenities. Only a handful of the island's caves, however, are reasonably accessible. Mallorca protects many of its caves by surrounding them with rugged terrain and jagged cliffs, but the island rewards those who pass its tests with indescribable, untouched beauty. Xisco was often a recipient of the island’s hard-earned spoils and his desire for more was impossible to satisfy.

 

After checking to make sure they had everything they’d need, Xisco and Guillem walked to the mouth of the Sa Piqueta cave. It was a system Xisco was largely familiar with. In 2006, he was credited with discovering connections between Sa Piqueta and two other nearby cave systems. Today, Xisco and Guillem would dive almost 1 kilometer from the entrance to Sa Piqueta to measure and map the tunnels and chambers they discovered. The system was a mix of dry and underwater cave sections. After crouching to enter the relatively small cave opening, Xisco and Guillem would need to walk through one of Sa Piqueta’s dry sections to access the water. Once there, they made final preparations, secured air tanks to their backs, and slipped into the water before disappearing below the surface.

 

If you’re unfamiliar with cave diving, there are few hobbies with more potential danger. There’s a lot that can go wrong when you’re underwater in cramped tunnels, wearing tanks filled with an ever-dwindling supply of air. In an instant, a routine dive can become a struggle for survival. Official figures are difficult to come by, but a study of cave diving from 1969 to 2007 estimated that about 10 cave divers die every year from a population of only a few thousand who participate in the sport. Scuba diving, by comparison, has a fatality rate of 1 in 15,000. A separate study published in 2015 estimated that the death rate among cave divers has decreased since 2007, but the number of trained cave divers who die in accidents has doubled. Xisco was one of Mallorca’s most-experienced cave divers, but as the shifting trend indicates, experience does not provide immunity from the potential dangers of the sport.

 

Xisco and Guillem began working their way through the first section of the cave. Ahead of them, they saw near-perfect conditions. While darkness grew the further they went from the entrance, their flashlights illuminated nothing but crystal clear water ahead. Today’s dive would be similar to hundreds of others the pair had completed. It would take about an hour to reach their target section 900 meters from the cave entrance. They’d spend another hour exploring, then another hour getting back to where they entered the water. Both open-water and cave divers have to pay close attention to how much time they expect a dive to take so they can bring enough air. The pair brought enough tanks for the full trip plus an extra hour of emergency air each should anything unexpected happen. This is a routine practice among cave divers.

 

One of cave diving’s more common dangers is how quickly visibility can change. Conditions can go from those Xisco and Guillem were enjoying to zero in an instant. This occurs when water becomes what divers call “silted out.” Cave diving differs from open-water diving in a variety of ways and one of the biggest is how divers propel themselves. Scuba divers can flutter-kick and make movements without a need for caution, but cave divers learn specialized kick techniques during certification courses. Cave diving kicks require minimal leg and foot movements that still efficiently move divers in the desired direction. Small movements can help prevent the sediment lining the walls, floors, and ceilings of caves from becoming suspended in the water. If that sediment is disturbed, it can create conditions similar to the inside of a well-shaken snow globe. It’s normal to stir up some silt during dives, but things can get out of hand quickly if a diver comes in direct contact with the surrounding rock. If you’ve ever been driving in the fog at night and turn on your vehicle’s high beams, then you have an idea of what being silted out is like. Light only illuminates the fog and magnifies its thickness, removing the ability to see more than a few feet ahead of you. This is difficult enough on the road, but when facing similar conditions underwater in a confined space where visual cues are the relied-upon way to tell up from down, just determining where you are and where you’re going can become challenging.

 

A guide rope is critical in such a scenario. Guide ropes, or guidelines, are what you might expect — they serve as guides for divers. Caves popular with divers often have permanent guidelines from the entrance through its various corridors and chambers. If a cave doesn’t already have one, divers will set their own. Often just a thin nylon rope, guidelines can be affixed with plastic markers to alert divers to certain conditions ahead or point them in the right direction at a fork in the tunnel. Most importantly, the guideline is always attached to a cave’s entrance and line markers often indicate which direction that is. In silted out conditions when divers can easily become disoriented without visibility, the guideline is a literal lifeline. By maintaining a hold on it, divers can work their way back to safety no matter what visibility is like.

 

Such a scenario was far from their minds as Xisco and Guillem continued their journey in the pristine conditions of Sa Piqueta’s waters. After an hour’s journey, they reached their intended destination and began exploring. Xisco began to collect rock samples while Guillem measured the dimensions of a nearby chamber. The two spent their allotted hour seeing what they could discover before Xisco looked at his dive computer and saw that he had gone through a third of his air. Knowing Guillem’s air consumption was likely similar, Xisco estimated they had enough air for two more hours, maybe two-and-a-half, tops.

 

Xisco met Guillem at a nearby fork in the tunnel and pointed to his air gauge, indicating it was time to go. Guillem gave him the thumbs-up and they began making their exit. The swim back started in a wide area of the tunnel, but as they proceeded the walls narrowed. As the rock surrounding them got closer and closer, it became apparent that the conditions they enjoyed on the way down had changed. They had taken great care to keep from stirring up sediment on the trip in, but their presence was enough to completely silt out their intended route. This wasn’t an unfamiliar scenario for such experienced divers. They knew exactly what to do — locate the guide rope. Grabbing onto it, Xisco and Guillem began moving hand over hand through the silt. As the tunnel got tighter, Xisco’s tanks would drag and catch on the rock walls. This made the silt surrounding them more dense and their visibility was now near zero. As long as they kept on the guide rope, they’d be just fine.

 

Continuing to progress through the tunnel toward the surface, Xisco suddenly held the end of the guide rope in his hand. To their horror, it didn’t go any further. Intact on the way down, the guide rope had been cut somehow, likely by a falling rock that was dislodged by the divers on the way in. Xisco normally relished the opportunity to explore uncharted territory, but not like this. Neither diver had encountered a snapped guideline before. While it’s true that danger doesn’t care how many cave dives you’ve done, experience is a great asset for divers who find themselves in trouble. 

 

One of the most dangerous things a diver can encounter underwater is another panicked diver. One hysterical diver puts everyone around them at risk. Not only do panicked movements make silt-outs worse, they can cause regulators to be knocked out of mouths, masks to be ripped off, air to be consumed too quickly or a host of other consequences.

 

Calm divers think and react rationally, and Xisco and Guillem were calm divers. After briefly grabbing around for the next section of guideline, Xisco pulled out a laminated map of the cave system. With just enough visibility to see his friend and the map, he looked at Guillem and pointed to a nearby artery. Xisco was certain it led to one of Sa Piqueta’s dry chambers, which would contain a breathable air pocket. If Guillem could find it, he could surface there and conserve what was left in his tanks. Meanwhile, Xisco would remain behind to continue searching for the other section of guide rope. 

 

Guillem turned toward the tunnel and almost immediately disappeared into the silt. After a bit of a swim, he located the chamber and surfaced. Sure enough, the chamber housed a large air pocket. Back in the silt out, Xisco felt around blindly for the section of guide rope attached to the cave entrance. In his efforts to find it, he lost track. When he thought to check his air gauge, Xisco’s eyes widened. He had been searching for the rope for about an hour and the physical effort to find it caused him to consume more air than he intended. His supply of emergency air wouldn’t even last another hour and the pair of divers were still almost 1 kilometer from the exit. Even if he found the rope right now, he wouldn’t have enough air to reach the surface. They were in trouble and Xisco knew it as he started toward the chamber where Guillem waited.

 

When Xisco surfaced with the news, Guillem’s heart sank. They were stuck with little chance of being found in an unmapped chamber of the underwater maze. If they were going to make it out, they were going to have to somehow do it themselves. They needed to regroup and talk through the options. They got out of the water and pulled out the map. Xisco knew of another way out of the cave and it was a virtual certainty that conditions on this route would be clear. It would also have an intact guideline. It was the perfect solution if their air tanks weren’t so spent. With enough air, the situation would have been little more than a hiccup in an otherwise routine dive, but the math didn’t line up. Even with the air Guillem saved by waiting in the chamber’s air pocket there simply wasn’t enough for both of them to make it now that Xisco’s emergency supply was depleted. There wasn’t enough air for both of them to make it. There was, however, enough for one of them to make it.

 

Xisco explained his plan. Guillem would take all their remaining air, swim the longer route to the surface, and get help. With Xisco’s stocky build to Guillem’s thin physique, Xisco knew Guillem would move faster and consume less air than he would. Xisco had also spent way more time in dry caves than Guillem so he was more accustomed to breathing the type of air found this deep inside caves. Once alerting rescue, Guillem would be able to direct divers to the unmapped chamber and Xisco would be out in no time. 

 

The outcome was anything but certain, though. Cave diving is normally done in groups of at least two people. Solo cave diving is not unheard of, but the risk is much higher. Solo divers also bring more supplies than a dive might call for and tend to dive within their limits. With Xisco the more experienced of the two and the new way out being more complex than the original way in, Guillem making it to the surface to get help was not guaranteed. If Guillem died on the way back, Xisco would almost certainly be dead soon after. If they stayed together in the chamber and waited to be found, they stood even less chance of both of them making it out alive, so they had little choice. Xisco would stay, Guillem would go. Guillem readied himself for the swim to the surface and soon, Xisco would watch him disappear into the water. They didn’t make a big deal out of separating before Guillem left, but Xisco couldn’t help but wonder if he’d see his friend again as the last of the bubbles from Guillem’s tanks broke the surface of the chamber’s lake.

 

Now alone, Xisco couldn’t dwell on it. He needed to turn his attention to survival. Cave divers travel light and Xisco had few usable supplies with him. He had no food and there was no food source inside the chamber. He always carried three flashlights on dives but two of them were dead and the third was on life support, so it was just a matter of time before he’d be engulfed by thick darkness. 

 

The chamber wasn’t completely inhospitable, though. Measuring 80 meters long, 20 meters wide and with a gap of 12 meters from the water to the ceiling, the chamber had plenty of room so the air pocket was substantial. There was a flat section of rock where he could lie down and he even found a supply of fresh water. Sa Piqueta’s underwater tunnels were full of salt water, but an unknown source was emptying fresh water into the lake that would remain on the surface. By skimming the top layer of the lake with cupped hands, Xisco could drink his fill to remain hydrated. In any other set of survival circumstances, this would buy him significantly more time should a rescue effort require it.

 

The air inside the chamber, however, easily canceled out the extra time staying hydrated provided. Above ground, the air we breathe contains around point-zero-four percent (.04%) carbon dioxide. Inside caves, carbon dioxide is the most influential of any gas. In fact, caves exist largely because of carbon dioxide. The gas plays a significant role in cave formation and is responsible for creating open spaces and mineral formations. It’s the whole reason Xisco has a cave to explore or an air pocket to sustain him, but while it’s great for caves, carbon dioxide can be a killer for humans. Cave air has a much higher concentration of carbon dioxide than above ground and the further away from a cave entrance, the higher the concentration of carbon dioxide. Air with a carbon dioxide concentration of 2 percent has little impact outside of a slight decrease in cognitive and motor abilities. At as little as 3 percent concentration, carbon dioxide becomes potentially lethal.

 

The air entering Xisco’s lungs inside the chamber was saturated with 5 percent carbon dioxide, putting him at significant risk for hypercapnia, or carbon dioxide poisoning. Just moments after Guillem left, Xisco’s noticed his breathing already becoming slightly labored — one of the first signs of hypercapnia. In mild forms, carbon dioxide poisoning can cause drowsiness, headache, dizziness, hyperventilation, and disorientation. Severe hypercapnia can cause hallucinations, paranoia, panic attacks, irregular heartbeat, and even organ failure, brain damage, coma, and eventually death.

 

While he had been in air this saturated with carbon dioxide before, his previous experiences were limited to time frames measured in minutes. More than an hour had passed when Xisco first surfaced in the chamber and removed his regulator to take his first breath from the air pocket. The way Xisco saw it, there was little he could do and it was for the best. To slow the rate of carbon dioxide building up in his blood, Xisco laid down on the chamber’s only flat dry surface and focused on holding his breath as long as he could between slow inhales and moving only to urinate or hydrate. He also kept his last remaining flashlight turned off and turned it on only to get into the water for a drink or check the time.

 

Despite feeling the early symptoms of carbon dioxide poisoning, Xisco was hopeful in his first hours of solitude. With nothing to distract himself, all he could do was lay there with his thoughts and wait, which warped his sense of time. Seconds passed like hours. When he was certain he had been trapped in the chamber for seven or eight hours, he checked his dive watch and found only three had passed. Not long after, his dive watch died. Time itself might as well have stopped as the hope he began his ordeal with quickly started to fade.

Completely exhausted by this point, Xisco tried to find relief in sleep, but an intense headache had set in from growing hypercapnia. Between aching temples and a racing mind, sleep wouldn’t come.

 

Held hostage physically by the chamber and mentally by his own brain, Xisco began entertaining his fears. A growing dread that Guillem didn’t make it eventually consumed Xisco. He was now certain that his dear friend and only hope of rescue died on the journey out of the cave. As a result, the chamber keeping him alive and slowly killing him at the same time would become his tomb.

 

Less than an hour after he left Xisco in his chamber, Guillem surfaced where he and Xisco entered the water. He spit the regulator from his mouth and deeply inhaled the above-ground air. He was able to control his breathing during the entire journey to the top despite his rush to get there, but still nearly spent the air remaining in his and Xisco’s last tanks. Guillem quickly got out of the water and ran to the mouth of the cave, stopping only when he got to the car. He pulled out his cell phone and his hands shook as he dialed the number to Grup Nord, Mallorca’s official caving organization.

 

An hour later, the island’s top cave divers were suiting up at the entrance to Sa Piqueta. The two divers most familiar with the cave would go in first to attempt to reach Xisco’s chamber. Guillem pulled out the laminated map Xisco had given him and used a waterproof marker to draw a big red X over the location of the chamber. He handed it to the divers and they turned to enter the cave.

 

One of the divers making the first attempt to get to the chamber was Bernat Clamor, another close friend who had almost as much cave diving experience as Xisco. Knowing that the original route to the chamber was without a guide rope and likely still silted out, Bernat started down the tunnel Guillem took on his way back. Two hours later, he and his partner resurfaced. Now the alternate route was impassable. In his rush to get help, Guillem had stirred up the silt on his way back and visibility on that route was now almost zero. The divers made it 300 meters in before Bernat couldn’t read the markers indicating where to go at a fork. He knew diving in those conditions was pointless and an unnecessary risk, so they turned back. Like Xisco, his rescuers would have to wait. How long was uncertain, though. Silt outs can take hours, or even days, to clear.

 

Back inside the chamber, Xisco’s headache had become more intense and his breathing more and more labored. Unable to sleep, see, or move around much, Xisco could only stare into the darkness above him and continue thinking. He thought about his mother, his 15-year-old son and 9-year-old daughter, and a sister-in-law battling cancer. He wondered if his ex-wife had been notified yet. A year earlier, the couple split and the divorce devastated Xisco. He wondered if she was worried about him, or if she told the kids where their father was. They were too young to lose their father and he wondered what would happen to them when he was gone. 

 

His thoughts were interrupted by a light breaking through the darkness in the lake. This was followed by the sound of bubbles, like those of a surfacing diver. He sat up, dizzy from the sudden movement, and flicked on his dying flashlight. This was it. He was going home and he was ready to greet his rescuers. He shined the flashlight around where he thought he heard the bubbles, but there was nothing. No bubbles, no light, no surfacing diver, and no rescuers. He was hallucinating, one of the surest signs that carbon dioxide poisoning was reaching severe levels. The reality hit him hard as he laid back down on his rock.

 

At one point, he began hearing what sounded like someone drilling into the rock above him. He was sure it was another hallucination, but the noise persisted. This time, it was real. As attempts to reach him were on hold because of poor visibility, the rescue team was able to access a dry area above where they thought Xisco was. Desperate to do anything but sit around and wait, rescuers had the idea of drilling a hole into the chamber to pass food and water through. It was the Xisco’s first sign that Guillem made it out alive and that help was on the way, but the noise suddenly stopped and never restarted. Rescuers couldn’t get through the rock and Xisco’s hopelessness sank to its lowest levels.

 

Above ground, Sa Piqueta's entrance was active. Divers continued planning, police set up tents and barricades to keep a growing crowd and reporters at a distance, and medics waited to attend to Xisco as soon as he made it out. It was now 9:30 on Sunday night and Xisco had been trapped for more than 30 hours. The rescue effort was taken over and directed by the Civil Guard, the oldest of Spain’s two national police forces. After listening to divers, the officer in charge made the call to wait until the next morning to attempt reaching Xisco again. Several of the divers disagreed with the decision, with one pointing out that it’d be too late by then. They were at the mercy of slow-settling silt. Unsuccessful attempts to maneuver in it would only prolong the visibility issues keeping them from rescuing Xisco.

 

Below their feet, hallucinations, thoughts, and the inability to sleep tormented Xisco. He started to wonder how much longer he could last. He didn’t know what was happening above him, if anything at all. He was unsure of how much time had passed since he heard the drilling, but it felt like forever. Lacking any other sign of a potential rescue, Xisco questioned whether the drilling noise he heard was real after all. If it was a hallucination, he could be sure that Guillem was dead and that he would be next. Xisco wondered how long it would take. Would carbon dioxide poisoning kill him or would something else get to him first? What would it feel like? Carbon dioxide had dulled much of his ability to think clearly, but he suddenly remembered one of the tools he had stashed in his dive gear on the other side of the chamber.

 

Xisco turned on his flickering flashlight and eased himself into the water. He swam over to his gear and patted around. When he felt what he was looking for, he pulled it from his gear and paddled back to his rock and laid down. On his chest, he held the folded pocket knife he just retrieved. If the carbon dioxide took too long to kill him, Xisco would take care of it himself. In a very real sense, it was the only control he had right now. He was in no rush to use it, but if the time came, he wanted it nearby.

 

It was late Monday morning when divers finally got the OK to resume rescue attempts. Another set of divers hurried into the cave and entered the water. With every advancing meter, their moods lifted. It wasn’t completely clear, but the silt on the alternate route settled enough to see the markers on the guide rope. To remove any potential of getting lost or delayed on the way down to Xisco or the way back with him, one of the divers went down the guideline and cut every offshoot at every fork that didn’t lead to Xisco. After two hours, they resurfaced and reported that they almost made it to Xisco and the visibility was good enough for the next divers to reach him.

 

Bernat leapt to his feet when he heard this and grabbed his tanks. Within minutes, he was underwater following the guide rope straight to the chamber. An hour had passed when Bernat thought to himself that he must be close. Inside the chamber, Xisco was reeling from another sleepless night and growing hypercapnia. Once again, he heard bubbles breaking the water’s surface. His last remaining flashlight was dead now so there was no use in reacting to the noise. He was sure it was just another hallucination anyway. Just like before, he saw light flickering across the ceiling of the chamber. As Bernat surfaced inside Xisco’s chamber, he was almost certain he was about to find his friend dead but he pulled himself out of the water and started calling out to Xisco.

 

His hallucinations hadn’t called his name before nor did any of them sound like Bernat. Xisco sat up expecting another disappointment, but saw Bernat walking toward him. Hallucination or not, Xisco got to his feet and embraced Bernat with a sudden jolt of energy. Xisco’s hug was the strongest he could manage. It was an expression of joy as much as it was to be sure Bernat wasn’t another hallucination. Satisfied that he was real, Xisco’s first question was of Guillem. Xisco was certain of the answer but asked anyway. Bernat smiled and told him that Guillem was alive and waiting for him at the surface. Hope returned and Xisco, once contemplating using his pocket knife to end his suffering, was going home.

 

Not right now, though. Bernat handed Xisco some glucose gel packets to restore some of his energy and the two continued talking so Bernat could gauge his condition. Once Bernat knew Xisco was mentally fit to take the long trip back, he asked if he could wait a little longer. Bernat would return to the surface and let the team know Xisco was alive. The next divers would be right behind with air tanks and they’d guide him out. Being unable to leave immediately could have deflated Xisco, but now that he knew he was going to be rescued and with the glucose gel bringing his energy back, Xisco said he could wait another day if he had to.

 

He didn’t have to wait that long. Four hours after Bernat’s visit, the next divers arrived. They brought tanks filled with Nitrox, a mixture of nitrogen and twice the oxygen of air above ground. Xisco put the regulator in his mouth and took the first deep breath he had been able to take in days. The Nitrox quickly had Xisco feeling like himself again. The brain fog cleared and the brutal headache finally started to release its grip. Eager to escape and physically ready for it, Xisco told his friends he was ready to go.

 

At 11:10 on Monday night, after 60 hours trapped in the chamber, Xisco walked out of Sa Piqeuta under his own power. The crowd that gathered erupted in cheers. As promised, Guillem was right there waiting for him. The two embraced for a moment, but they didn’t have time to talk. Despite appearing to be OK, Xisco needed immediate medical attention and was whisked away in an ambulance. On top of dangerous levels of carbon dioxide still in his blood, Xisco’s internal temperature had dropped to 32 degrees celsius (89.6 F) and he was at risk of hypothermia. After just one night in the hospital breathing pure oxygen, Xisco was well enough to go home.

 

The day after his rescue, Xisco watched the TV coverage of the rescue operation and burst into tears. He was overcome with gratitude for the 60 rescuers who worked around the clock to get him out of the cave alive, the crowd that held vigil, and those who watched the coverage at home, offering prayers and holding out hope of a happy ending. 

 

You might expect this cave diving experience to be Xisco’s last, but he never once considered giving up his hobby. Just one month after the incident, he even returned to Sa Piqueta and visited the very chamber that held him prisoner for almost three full days.

 

His dives since being trapped, haven’t been without incident unfortunately. In 2022, Xisco was involved in a cave dive that turned into a strangely reminiscent situation. Xisco and two other divers were exploring one of Mallorca’s other cave systems when one of the divers was separated from the group during a silt out. Desperate and running out of air, the diver found a cave chamber with an air pocket and waited until he could be rescued. When the diver was rescued just seven hours later, he jokingly asked his rescuers what took them so long.

 

Among the divers of Grup Nord, it is tradition for the first diver to explore a new cave or section to name it. Guillem may have been first to see the chamber, but the honor of naming it went to Xisco. He took stock of all he overcame during those 60 hours stuck inside the chamber. The way he saw it, his survival is a product of three miracles — finding a chamber with air in it, surviving for so long breathing such toxic air, and escaping the cave with his life. 

 

Today, the chamber that trapped Xisco is known as The Room of the Three Miracles.