Pitt, however, stayed in control when he hit the water. He kicked his legs hard, driving his opponent deep. With his diving experience, he figured he could outlast Pablo in the water, and pressed on the rail to drive him as far down as possible.

Focused on his attack, Pitt didn’t notice the pull of the swirling water. He was surprised, though, to quickly feel pressure in his ears, and he waggled his jaw to clear them.

Slowly recovering from the shock of impact, Pablo’s first instinct was to wrestle away the steel rail. But Pitt clung tight, using it to press Pablo deeper. Pablo finally came to his senses and realized he needed air. He pushed himself away from the rail, kicking to the side to escape Pitt.

But a strange thing happened. Instead of ascending, he was drawn deeper by an unseen force. Unnerved, he reached back and grabbed the rail while kicking furiously.

On the opposite side of the rail, Pitt stopped kicking, but another ache in his ears told him they were being sucked to the bottom.

The two men had fallen into the lock chamber directly over one of the drainage wells that dotted its floor. When valves in the wells were opened, the chamber’s water would drain through them into a lateral culvert, which fed an even larger culvert built into the wall. At over eighteen feet in diameter, this huge pipe emptied into Miraflores Lake.

Near the surface, the swirling of the draining water was barely noticeable. But at the bottom of the chamber, it became an inescapable whirlpool. Like Pablo, Pitt briefly let go of the rail and tried to kick to the surface. But the suction of the water refused to release its grip. Pitt brushed against Pablo in the turbulence and regripped the rail, positioning himself parallel to the bottom.

The draw of the water accelerated, pulling them forcefully to the well’s four-foot-wide mouth. Pablo fought the downforce, but his legs and torso were sucked into the pipe. The rail would have been swallowed also, but at the last second Pitt muscled it sideways. It clanged atop the circular concrete well, jerking both men to a halt. Neither realized how hard the water had been pulling them and both nearly lost their grip.

The impact threw Pitt off balance, and his legs were sucked into the well. The rest of his body followed, and he found himself hanging side by side with Pablo, clinging to the steel rail overhead, as thousands of gallons of water rushed past them. No longer concerned with battling each other, each man fought for his life.

Their descent had taken only half a minute, but because of their exertions both men were out of air. Pablo had fought to maintain his breath since hitting the water and now he began to struggle. His heart raced and his head ached. The fear of drowning flooded his thoughts, and he panicked.