It starts in the pool.

A soldier treads water with his rifle above his head then drops his equipment and swims away.

You might not associate swimming with being a sniper, but it's all about proving mental toughness.

"We want to see who gets stressed out easily, who can overcome that, who can bring the guys together and make them work through any fears or stress that they have," said instructor Staff Sergeant Tom Dennehy.

From the pool, the soldiers run in wet clothes in the cold weather to the shooting range. 

The soldiers have been identified as possible candidates for sniper school. 

But first, they need to prove themselves. 

If they're successful during this week full of tests, they could be recommended to go to sniper school in the future - something the soldiers want very much.

"It's something that most kids look up to, like, 'my big brothers a sniper in the Army,' you know? It's pretty cool. I want to prove something," said Private Austin Storts, one of the candidates.

Once they prove they're mentally and physically tough enough to get the job done, the soldiers need to prove they're a good shot.

We got a glimpse of target practice from behind the glass.

"We gotta be those guys that if bullets are flying over way, we gotta stay down and remain cool and pick our targets and take our time with what we're doing," said Dennehy.

It's a lot of hard work with no guarantee of making it to sniper school. 

Despite that, you might be surprised to hear some soldiers called the experience fun.

"It sounds kind of weird and crazy, but I actually like pushing myself.  It's a suck fest, but it's pretty cool," said Storts.

The soldiers running the course say of the nine soldiers going through selections, very few of them will actually make it to sniper school.