Organizers of the Merrell Down and Dirty Mud Run in Philadelphia said more than 5,500 people came out and got dirty to raise money for a non-profit. The organizers said competitors braved a muddy obstacle course including a ladder wall, hurdles and a tunnel Sunday in Fairmount Park to raise money for Operation Gratitude, which sends care packages to members of the U.S. armed forces, the Philadelphia Inquirer reported Monday. The event included 3.1-mile and 6.2-mile courses for the adults and children's courses of a mile and 100 yards. Organizers said they used 12,000 gallons of water to create the course.