It seemed like a safe exercise.

Although Navy rules said scuba dives below 130 feet could be conducted only in cases of “operational necessity,” none of the divers seem to have realized that did not include training, the report said.

The men were asked if they wanted to make the dive. Abdul-Mutakallim testified that he and Reyher knew of a diver who declined to make a dive during training and suffered unspecified “backlash.”

Plus, most of the divers thought they had to pass the super pond evaluation to be deployed.

Everybody said yes, they wanted to make the dive.

The first two divers to go down from the tending boat reached only 100 feet before the line linking them to the surface became “rats nested,” or tangled.

Their surface tender, Chief Navy Diver John O’Donnell, yanked the line four times to abort the dive, and the two men surfaced.

Reyher and Harris were next.

Their dive supervisor, Fernando Almazan, a 14-year Navy veteran and a diver first class, had calculated that the men would have 11 minutes of air, not enough time to survey the sunken helicopter.

But it should be enough to see if they could spot the wreck and come back.

Almazan instructed them to start back up four minutes after they submerged. Ascending would require five minutes. He told them to stay on schedule and not touch the bottom.

Reyher and Harris, each wearing a wet suit and a single air tank, began their descent.

At the 3:30 mark, O’Donnell gave them four pulls to abort the dive and got what appeared to be four pulls in reply. But he was confused. He told Almazan he wasn’t sure “what they just gave me.”

O’Donnell hauled in about 20 feet of the tending line. Bubbles rising to the surface suggested the divers were coming up.

Suddenly, the tending line went tight. The more O’Donnell pulled, the tighter it got. He realized that if the divers were snagged, pulling would make it worse. Or maybe they were swimming down to free themselves. So he fed out some line.

Almazan told him to stop. The bubbles coming to the surface began to increase alarmingly. Almazan asked an evaluator in the boat if this was part of the drill. The answer was no.

The Navy report suggested that the increased bubbles could have been air rushing from the scuba tank regulators malfunctioning in the cold water or the divers breathing heavily because they were running out of air.

Almazan directed Navy Diver Third Class Austin Noone, who was standing by with O’Donnell in the boat for emergencies, to go down and help.

Noone, who had never done a 150-foot dive in scuba gear, made it to 100 feet, but he, too, got tangled in the tending lines and was pulled up.

Reyher and Harris had now been underwater 12 to 15 minutes. No more bubbles were coming to the surface.