Marcus Nelson Pringle couldn't help but smile Sunday as he waded through waist-deep muddy water.

The 30-year-old Los Angeles County man had just run nearly five miles — facing numerous obstacles — and ended up at the so-called Triple Threat of the annual Mud Run at Camp Pendleton. He walked through a roughly 43-foot mud pool, then jumped over a 5-foot wooden barrier, into another mud pool, got back on land, went into another mud pool, crawled through an 18-foot rubber tube, and then started running again. He had another 1.2 miles to go.

Nelson Pringle is a connoisseur of mud runs, a type of obstacle course race similar to military training, and was participating in his eighth. He said the challenge of mud runs are what keeps him interested and coming back.

"I normally hate running," he said.

Roughly 7,500 people participated in the 26th annual Mud Run on Saturday and Sunday, a rare opportunity for the public to come on one of the nation's largest Marine Corps bases. The run is organized by the Marine Corps Community Services department, with money earned going toward recreational activities for Marines on base and their families.