Phase One continues...the men are determined to survive the physically and mentally rigorous program and remain injury free. New students, injured in previous classes, are added to Class 234. With Hellweek looming, they learn basic lessons of survival, hoping to be one of the few to become a Navy SEAL. By the end of week one, half the class is gone.

For 24 hours a day, six days in a row, students are put through a demanding set of obstacles designed to test their commitment to becoming SEALs. Cold, wet, hungry and sleep-deprived, the men struggle to prove their resolve as each test is followed by a more difficult one, pushing the psychological limits of even the toughest competitors. Hellweek is the ultimate eliminator – ending with only 19 contenders.

Meet the 83 men of Class 234 who have been accepted into BUDS, the training program that forms the Navy SEALs, one of the most elite fighting forces in the world. Watch as they tackle Phase One, a physically grueling course designed to weed out all but the toughest and most dedicated. This is only day one of 26 weeks of unimaginable physical and emotional strain. Most will quit within the first weeks.

By the second week of BUDS training, many of the students have already dropped out. The remaining men still have 24 weeks of hardship. Students who are failing physically are put before the review boards where instructors will decide if they are dropped for lack of performance or rolled to the next class for medical leave. Each week they must improve, they must run faster and swim farther. Individuals do not survive, teammates do. Hellweek, the harshest part of training, is still on the horizon.

Underwater testing begins in both the ocean and pool in what may be the most difficult test of all. The men are immersed with hands and feet tied and competing at underwater swimming, overcoming their panic and fear. They undergo advanced scuba and re-breather training and the SEAL instructors weed out those who just can't make the grade.

The men who've made it this far persevere -but still a few are pushed past the limits of their endurance. Witness the last months, weeks, days and minutes – discover which of these courageous souls graduate and become a U.S.