Most people would not stand a chance at the 8th Annual Recon Challenge. The event happened at Camp Pendleton on Thursday and Friday.
The challenge, which is open to the public to watch, is about as physically taxing as it gets.
Christopher May is one of 44 Reconnaissance Marines competing.
"[It's] absolutely horrible," May said about the challenge. "Most years I don't get off the couch for two days."
He remembers how his friend Sgt. Caleb Medley got second place and he got third during the first year.
The grueling 25 miles tests competitors' mental, physical, technical and tactical reconnaissance skill-set. Participants go through a series of difficult obstacles and activities like hiking, swimming and firing weapons. They do it while carrying a rifle and at least 50 pounds of gear.
Recon Marines are built to endure a lot.
"Nobody loves being cold, wet and miserable, but we do it the best," May said.
It is how they bond.
Master Sergeant Scott Young is part of that Marine family.
"I'd give my life for any one of them," Young said.
Reconnassaince Marines are an elite group within the Marine Corps. There are about 400 stationed locally.
"We are the eyes and the ears of the commander," May explained.
They quietly rush into the unknown from the air, ground and sea, so it is safer for the troops who follow. Since it is inherently dangerous, they lose a lot of friends.
"We all know the risk when we go overseas and step into a gun battle," Young said. He added that it is even more difficult to lose a solid Marine and good friend on home soil during a training exercise."
That happened in 2013. As the jump master, Young was the last one to leave the plane at Perris Island.
"I counted all my jumpers, and I waited for the check-in on the radio and I was missing one, and I saw him streaming down to the earth," Young added.
He watched helplessly and headed toward another fallen brother. May was on the ground.
"I saw it," May said.
It was his friend Medley who died in that skydiving crash. That is why he is doing that "horrible" challenge.
"We carry their names up the mountain," May explained.
They do it to honor their fallen brothers.
"There's absolutely not a day that goes by that I don't think about him," May added.
They say the public can watch. Just go to the San Onofre gate at Camp Pendleton and tell the guards you are there to cheer the Recon Marines on.
