BELLE CHASSE, La. – Before the explosion, the oil spill, the declarations of “environmental crisis” or the emergency visit by President Obama, 126 oil riggers were passing another quiet night on the Gulf of Mexico. The skies were clear and the seas calm on April 20. Boredom and loneliness were the primary concerns.

Matt Hughes lifted weights in the gym before his midnight shift. Kevin Eugene lay down on his queen-sized bed and turned on ESPN, thinking television might make him feel closer to land. Other men watched action movies in the theater or played poker in the lounge.

They called the Deepwater Horizon their “floatel,” because the rig was a world unto itself: an isolated tower on 5,000-foot-deep seas, with only scratchy satellite phones and the occasional helicopter to bridge the 50 miles to Louisiana shores.

Wyman Wheeler, a 39-year-old oilman, was busy packing. He was 20 days into a 21-day hitch, scheduled to fly back to Houma, La., by helicopter at 6 a.m. and then drive four hours to his home in Mississippi.

Like most of the men, he worked on the rig for 21 days at a time, enduring 12-hour shifts, seven days a week, so he could spend the next 21 days at home. He called his wife, Rebecca, and spoke to their two young children. “One more night,” he said. Then he promised them a vacation to Texas later that week.

Wheeler hung up the phone, changed into his coveralls and walked out of his room and down the hall toward the tool room, then stopped. The hall reeked of gasoline. The lights flickered. Popping sounds echoed from overhead. Suddenly the door to the tool room seemed to be breathing, as though someone was pushing on it from the other side.

THUDS, CHAOS AND CONFUSION

What happened next would be the last thing Wheeler recalled: The door blew off its hinges and barreled toward him, even before he heard an explosion.

In the weeks that followed, dozens of scientists would analyze the evidence and debate the damage. They would conclude that a gigantic blast of gas, oil and mud had roared up from the drilling zone three miles below, bursting through the floor of the Deepwater Horizon and sparking a historic fire.

Coast Guard rescuers who survived Hurricane Katrina would call it an extraordinary disaster. Experts would fly in and determine that oil was leaking into the Gulf at the rate of 210,000 gallons per day, threatening wildlife, fisheries and coastline across the southeastern United States.

It would be two weeks before many of the men at the epicenter of the disaster felt ready to talk about it. And when they did, they would describe the first moments simply in terms of sensory terror: two deafening thuds, followed by chaos and confusion.

Eugene, who had been drifting to sleep, rushed out of bed in underwear and a T-shirt. He was a cook working for a catering company, not an oilman, and strange noises always made him nervous. He reached into a closet for his life vest and hard hat — a habit instilled by the rig’s weekly fire drills — and ran out the door without socks or shoes.

A shrill alarm rang over the loudspeakers, followed by an announcement for the 126 men to make their way to Lifeboats 1 and 2, the sole ones that remained intact after the initial explosion.

Only when Eugene ran upstairs did the extent of the disaster become clear. The deck, once as large as two football fields, now measured three-quarters of its original size, and some of it was on fire. Pieces of machinery were raining down from the derrick, 200 feet overhead.

More than 100 men had crowded against a railing near the lifeboats — the only solid ground. Smoke billowed above. Flames grew nearby. The dark ocean waited 80 feet below. Explosions shook the rig every few minutes, spilling men and equipment across the deck.

“We’re waiting to get everyone here before we go!” a supervisor yelled to Eugene and the other men who were waiting near the lifeboats. Three minutes went by. Five. Seven. “This whole thing is going to explode,” Eugene said, terrified.

LEAP INTO DANGER

He looked down to the ocean, his eyes measuring the 80 feet. The lifeboats were supposed to be lowered to the water by automatic pulleys. He wondered whether the pulleys remained intact. He wondered whether the next explosion would be his last.

Nearby, Hughes, 26, of Malvern, Ark., gripped the railing to help steady his balance. He was still in his weightlifting clothes, with a life preserver now covering his T-shirt. He watched his co-workers idling by the lifeboats and thought: We are going to die waiting.

The flames acted like a torch to light up the ocean. Hughes looked down at the water. The seas were calm. “Screw it,” he thought. He would jump.

He put a wad of Copenhagen chewing tobacco in his mouth to steel his nerve. He climbed up the railing and looked down one more time, still hanging on. Clear the rig and land feet first, he thought. He held his breath and let go.

Capt. Alwin Landry looked across the ocean at the flaming rig and saw a flash of reflective gear dropping from the sky. He followed the shape to its splash in the water, wondering what it was, and saw a person bobbing in the sea. Soon there were more jumpers — three, four, five, all waving their arms for rescue.

Landry, 41, had been servicing the rig on a typical “grocery run,” using his ship, the Damon B. Bankston, to deliver supplies and special drilling mud. He’d been about to begin the long trip back to shore when, at 9:53 p.m., he heard an explosion and then saw a blinding green light.

‘THIS IS THE REAL DEAL’

Suddenly Landry was rushing to fish men out of the water, remembering an old bit of advice from his father, a volunteer firefighter: Be calm and give concise directions. But his father had never seen fire like this.

At the same time, an emergency call was sent to a private air-ambulance service and two Coast Guard stations. “This is the real deal,” the flight dispatcher told Raymond Mouton, 42, a flight paramedic at Acadian air med. Mouton and his colleagues stuffed the helicopters with blankets, bandages, backboards and collars to immobilize broken necks.

Acadian’s helicopter, painted with a fleur-de-lis flag, took off from Houma, at the edge of south Louisiana’s vast marshes. Four other helicopters and one airplane flew over the Gulf toward the wreck, pushing top speed. The rescuers flew in darkness, over uninhabited swamps.

Forty miles from the rig, they saw an orange glow flickering on the water that looked like a distant city skyline. Soon it was clearly a fire. Then, five miles out, it was an awe-inspiring blaze with flames burning 300 feet into the air and spreading across the water.

One mile from the wreck, Coast Guard Lt. Andy Greenwood put his hand against his window. It was hot.

Before the choppers arrived, the survivors started to make their way to Landry’s supply ship. Hughes, the jumper, swam almost a quarter of a mile to the boat, arriving with a bruised chest, numb toes and tobacco still tucked securely behind his lip.

Eugene, the cook, arrived in one of the lifeboats, which had finally descended to the water almost 20 minutes after the initial explosion.

Wheeler, who had been hit by the flying door, also arrived in the boat. He had been carried to safety by two other oilmen who had found him unconscious and with a broken leg, dislocated shoulder and burns on the back of his tattered coveralls.

The survivors boarded the ship using ladders, and some were carried on by Coast Guard rescue swimmers. Less than an hour after the explosion, the oilmen on the Damon B. Bankston ship lined up for a headcount.

Some had compact fractures or cuts to the head; others would later be wrapped in blankets and lifted into helicopters destined for hospitals. Rig managers marked the men off one by one as they counted, using a manifest to add the total: 115. They counted again. One hundred fifteen.

Eleven were missing.