From the SEAL website: "To become a SEAL in the Naval Special Warfare/Naval Special Operations (NSW/NSO) community, you must first go through what is widely considered to be the most physically and mentally demanding military training in existence. Then comes the tough part: the job of essentially taking on any situation or foe that the world has to offer."
The qualification training takes 26 weeks. If you pass, you are assigned to a SEAL team. Now the real fun begins. You can become a SEAL medic (a very important function in the unit), an officer, or a specialty team member.
This job is—by law—for men only. You have to have good eyesight, meet the minimum vocation aptitude scores, be a U.S. citizen, and pass physical requirements for divers.