CORONADO, Calif. — As Navy Ensign Brandon lay slapped by wave after black wave of frigid Pacific surf, his arms linked with a row of other would-be Navy SEALs, a cold but comforting thought surfaced from his murky consciousness: “No matter what,” he reassured himself, “they’re not going to kill me.”

Shaking uncontrollably in the cold brine, the slight, 22-year-old from Ohio dreaded the nighttime “surf torture” as one of the toughest ordeals of the SEALs’ aptly named Hell Week, designed to break down the bodies and wills of all but the steeliest young men.

Today, one of the Pentagon’s main dilemmas is how to get more candidates such as Brandon to outlast the trials of selection — without lowering standards — as it tries to expand the ranks of SEALs and other elite U.S. military forces for critical missions in the war on terrorism.

Facing their biggest deployments in history, as much as 80 percent of the combat forces of the 53,000-strong U.S. Special Operations Command — including Navy SEALs, Army Green Berets and Rangers, and Delta Force operatives — are committed in Iraq, Afghanistan and surrounding countries. That leaves too few for other vital missions, many of them clandestine, such as intelligence gathering and partnering with forces in nations where the United States is not at war, according to senior military officials.

Stepped-up war-zone rotations are cutting into training time, and shortages in the force mean hundreds of Special Operations jobs are unfilled, leading to more reliance on civilian contractors, they said.

“We as a nation are taking great risk” by having too few maritime commandos, said Rear Adm. Joseph Maguire, commander of Naval Special Warfare Command (NSWC) here. NSWC should have 2,200 SEALs but is undermanned by about 400 men on SEAL teams and scores of officers, he said.

The Pentagon in February announced a plan to add 13,000 more Special Operations troops to meet demands. But producing such highly skilled troops is not easy — especially as war, low unemployment and negative health trends such as obesity shrink the military’s overall pool of candidates.

Of all the elite forces, SEALs pose the biggest recruiting challenge. The Pentagon’s goal is to add 500 new SEALs in the next two years. Maguire says 2010 is more realistic. But the number of SEAL applicants has dwindled by hundreds in recent years. This year’s goal is to bring in 1,400 to try out, but by late April, only 364 had been sent to boot camp, according to Navy statistics. “We’re behind the power curve,” said Ed Kearl, a Navy recruiting official.

Ground zero for the push to create more SEALs is the rugged beaches and pounding surf off Coronado, where the young men of Basic Under Water Demolition/SEAL (BUD/S) Class 259 found out who had “the right stuff.”

The Start of Hell Week

It was a Monday night in May, about 24 hours into Hell Week for Class 259, and Seaman Brian was sitting on the beach next to his rubber dinghy, eating a chili-mac packaged military meal. For security reasons, all SEALs except senior leaders spoke on the condition that only their first names be used.

Similar to the rest of his class, Brian had no sleep, was soaked and shaking. He had muscle cramps from lunging with 15-foot-long sandy logs. His legs were chafed raw. “It’s like taking a piece of sandpaper to your skin for a week,” said Brian, 23, who is from Ventura, Calif.

As the sky darkened, the entire group knew what was next — surf torture (officially called “water immersion”), jumping on and off a pier and being hosed down with cold water.

Suddenly, Brian saw a friend stand and walk stiffly toward a bell hung on a wooden frame. Ringing the bell was how candidates dropped out. “Clang!”

“I was like, ‘Wow,’ ” Brian said.

Next, shocking everyone, the Class 259 leader, known as the OIC or “officer in charge,” got up. “Clang!” About 12 other recruits followed in a mass exodus. The class that started in March with 193 men was down to 100.

“It was a big psych for a lot of guys because our OIC left. That was hard,” said Brian, who dropped out the next morning, his right leg swollen with tendinitis.

The buckling of the class leader underscored how difficult it is to predict who will make it. “They don’t want to deal with the discomfort . . . it’s kind of frustrating,” said Capt. Christopher R. Lindsay, commander of the Naval Special Warfare Center. To help more pass, Maguire said they may eliminate some “water immersion” sessions.

Finding candidates in top physical condition also helps, but until recently, concerns over legal liability prevented potential recruits from being given a swim test. “They would get to boot camp and, ‘Oh, by the way they can’t swim,’ ” said Kearl, who said 70 percent of candidates were failing the test. “That’s a big problem.”

Now candidates must pass a 500-yard, 12 1/2 -minute swim test at the YMCA — and do at least 50 sit-ups, six pull-ups, 42 push-ups and a 1 1/2 -mile run — or lose their SEAL contract. Those who pass with minimum standards will earn a $1,000 bonus, and $2,000 goes to the best performers — but still only 60 percent succeed.

Maguire is also asking SEAL instructors to be less subjective in disqualifying candidates. But having “given enough flags away” to the families of fallen SEALs, he says he can’t compromise the highly competitive standards.

“Everything is a race,” said Lindsay, as the seven-man teams hit the surf Tuesday in the red dinghies they carry everywhere.

“If you drop the boat, I will cut your head off!” shouted a veteran SEAL instructor as he ordered laggard boat teams to race around and around a building — holding their boats on their heads. “Nineteen, 20, 21 . . . get back in line!” he barked to the slowest team.

Garrett, 23, of Hilo, Hawaii, felt his arms start to give way. “We would come in last, and obviously it was because of me,” he said. Teammates complained. Instructors put another recruit in his place to show he was the “weak link.”

At 4:30 a.m. on Wednesday, the 79 remaining candidates staggered out of the mud flats of the 65-degree San Diego Bay, looking like a scene from “Night of the Living Dead.”

“They’re basically zombies,” said Cmdr. Adam Curtis, looking on. Awake for 55 hours, the men could only shuffle. But they were expected to follow directions.

Brandon, a boat team leader, was having trouble.

“You’re trying to cheat me, Sir,” berated an instructor. Brandon’s team had paddled their boat by hand instead of swimming beside it in the last race. Now, they would pay the price.

“Prepare down boat — down boat! Prepare up boat — up boat!” the instructor spat commands with a bullhorn. Next the offenders had to roll in the sand.

“We’re going to have a little bath,” the instructor said, ordering them into the bay. Each time a device beeped they bobbed underwater, green light sticks glowing eerily on their life vests.

Hell Week is designed to simulate the rigors of a combat mission. “They can’t say ‘I quit’ because no one will come get them,” explained Command Master Chief Lu, a 25-year Navy veteran and instructor. The end result, Lu said, is impressive. On a recent tour in Baghdad, he fought side by side with former SEAL students and found that “I trusted them as much as guys I was with 20 years,” he said.

To qualify, over a six-month period SEAL candidates must swim 150 miles in the ocean and run more than 1,300 miles in sand wearing boots, and later they must learn to dive, parachute, shoot and conduct close-quarters combat.

Born from World War II underwater demolition units, Navy Sea Air Land teams focus on maritime skills, including diving, forced ship boardings, laying undersea charges and reconnaissance. But today, SEALs are occupied mainly on land. Most 16-man SEAL platoons are in Iraq training Iraqi forces, using snipers to watch for insurgents planting bombs and guarding Iraqi leaders.

New missions, many secretive, are creating demands for a more diverse force trained in language and culture. “We are a relatively white, non-Hispanic force. It’s nice to have someone who can blend in more,” said Capt. Gary Bonelli, NSWC chief of staff. Class 259 has only a handful of minorities.

SEAL recruiters this year are attending dozens of events, such as wrestling matches and “X-games,” manning a new call center, and offering a $40,000 bonus to all new SEALs, said recruiting chief Cmdr Duncan A. Smith.

Still, nothing can guarantee that recruits will have the tolerance for stress, flexibility and what Lindsay calls the “fire in the gut” that psychological studies show is critical.

By Friday morning, the class was down to 73, having lost a few more to pneumonia and injuries. In a finale, the exhausted recruits had to low-crawl from the beach to an obstacle course obscured with smoke and rocked by the blast of simulated grenades. Worming their way under concertina wire as instructors fired off blanks from rifles, they slid through a drainpipe into a muddy pool. Barely able to move his legs, Brandon dragged himself forward with his arms, third to last.

“You knew you’d never quit. . . . The courage, the mental toughness is contagious,” Lindsay told the bedraggled class on the beach afterward. “You guys are what we want to work with to become Navy SEALs!”

“Hooyah!” Class 259 yelled.

Relaxing later in dry clothes with a pizza and Gatorade, the victorious few reflected on how they made it. “It’s just putting one foot in front of the other,” said Brandon, rubbing swollen calves.

Still shivering, Airman Brandon said that after his body broke down, his mind took over. “The main thing I thought about,” he said, “was doing things that every guy dreams of doing, but few do.”