They are designed to be the best in the sea, air or land -- that's what SEAL stands for.
"It's a self-contained unit that can go any place in the world and literally do nothing but kick ass," said Richard Marcinko, a former Navy SEAL.
Recruits are trained to swim nearly 350 feet underwater with their hands and feet bound. They are taught to survive arctic conditions and endure exposure to tear gas. The SEALs basic training site is at the Coronado Naval Amphibious Base in San Diego County.
Only men ranging in age from 26 to 33 try out to become one of 2,500 SEALs.
Training takes two years and 75 percent don't make it through. Years of more field experience is needed to even be considered to be admitted to Team Six.
"By the time you get to Six, you're going to overcome any weak points that you have in any of those disciplines, or you're going to wash out and say you're a good SEAL, but you're not good enough for this," Marcinko said.
Marcinko started Team Six in 1980. On missions, they may jump from a plane 11 miles in the air, sit in deadly silence, camouflage themselves in any environment or hold their breath underwater for more than two minutes without releasing a single bubble.
They shoot with pinpoint precision, but Marcinko says their most deadly weapon is their mind.
"The body is only tissue," Marcinko said. "The brain controls it and the brain will push them beyond what you and I and normal people think the body can take."
The SEALs that killed Bin Laden had gone through thousands of scenarios before assaulting his compound.
The CIA provided enough detailed satellite pictures to build a replica compound where the teamed practiced.
For a time, they trained without knowing who their actual target was. But by Sunday, they knew the location of every gate and window and the exact height of the walls. By the time the SEALs ran out of the compound with Bin Laden's body, they could probably count the exact number of steps to the helicopter outside.