I am interested in knowing if there are any military style obstacle course trails that exist in a completely forested setting for the military, police, search and rescue, and so on, yet are open to the general public?

Ideally the course would have be to several miles/kilometers long and both natural and manmade obstacles would be incorporated together.

Do such military style obstacle course trails exist in a completely forested setting that open to the general public (in the USA)? Other countries may be added in as a complement.