Some soldiers who have already served in Operation Iraqi Freedom and other difficult missions are diving in to serve their country at a deeper level.

At the Special Forces Underwater Operations School (search) in Key West, Fla., Army and Air Force Special Forces undergo one of the most challenging courses in the military to become a combat diver (search).

"We train for infiltration purposes," said Air Force Mst. Sgt. Brian Bailey, an instructor at the dive school. "It's another method for getting to the job because our job isn't diving. This is just one vehicle to get us to our job and to sneak in, hopefully undetected, and that's the whole idea."

The training takes guts and stamina -- 25 percent of those who attempt the five-week training course fail to make the grade.

And it's not just failure that's at risk. In the school's 40-year history, several students have died during the dangerous training.

But the gains outweigh the risks, said one student. "I think it makes us a better asset to our teams," said Sgt Cameron Weatherbee, a combat student who recently returned from serving in Iraq. "The more experience you have, you become more versatile and it builds your confidence."

For security purposes, the Army won't comment on past deployments of the program's graduates, except to say that combat divers are called upon for only the most difficult operations.

"The graduates of this school are picked for the most challenging missions,'" said Major David Hsu, the dive course commander. "No one comes here because they want an easy day."

The skills of combat dive school graduates are widely respected, said Bailey. "A lot of commanders and a lot of people within our community take a look at the Special Forces diver graduates and say these guys, physically, can meet any challenge. If they can't do it possibly no one can."