Peter and his son Jake were certified divers who planned to do two dives from their friend’s boat. The night before their excursion, they pulled together their gear and realized that they only had one working regulator. The local dive shop was closed, and they would depart before it opened the next morning. But Peter wasn’t too worried—Jake could just use his octopus and they could dive together sharing a tank.

There are several concerns when starting a dive sharing a secondary regulator and tank. First, the backup regulator is an important piece of gear used for safety redundancy. In an emergency, this backup is used to share air. But if you’re already sharing air, there is no emergency plan. Second, the air in the tank is used much more quickly when two divers are breathing it.

Related Reading: Am I Ready to Take the PADI Rescue Diver Course?

The next day, on their friend’s boat, Peter and Jake were having a blast. The first dive went well; they swam shoulder to shoulder and stayed shallow—they even saw a pod of dolphins! Sharing the gear went off without a hitch, but now it was time for their second dive. With newfound confidence in their approach, the pair descended to 65 feet. About 25 minutes into the dive, Peter looked at their gauge and realized that they were very low on air. Sharing a tank led to faster air consumption than they had anticipated.

Peter looked at Jake with wild, deer-in-the-headlights eyes—a sign of distress or panic. Unsure what to do, and now with no air in their tank, Jake grabbed his dad’s arm and dragged him toward the surface. They didn’t make a safety stop. His decision was the right one; in an emergency situation on a dive within recreational limits, you should skip the safety stop.

At the surface, Jake called to the boat for help. By the time they got on board, Peter was barely breathing. A few moments later, Jake saw his dad stop breathing. While one friend administered CPR, the other drove the boat back to shore, but it was too late. Peter was pronounced dead at the hospital.

The coroner reported the cause of death as barotrauma due to acute decompression. Divers are trained to breathe continuously. But in a panicked, out-of-air situation, they may forget their training and hold their breath. When you ascend from depth too quickly and aren’t breathing normally, the pressure change can damage parts of your lungs and force some air into the bloodstream. This air in the blood can then lead to a serious complication known as arterial gas embolism or AGE. An AGE blocks blood flow to vital organs and can be deadly, as in this case. Unfortunately, Peter and Jake’s choice to share a tank and secondary regulator resulted in rapid depletion of their air supply and forced an emergency ascent that could have been prevented by both divers having full sets of gear and following their training.

Related Reading: How to Safely Enter and Exit the Water From a Boat

Lessons for Life

1 Dive with your own gear.

Only share air during training or an emergency.

2 Ascend slowly.

A controlled ascent is one of the most critical components of a safe dive.

3 Breathe continuously.

Never hold your breath while diving to avoid life-threatening injuries like AGE.