The basic rules are easy:

• You and your teammates must travel together at all times
• You must travel under your own power for the entire event (i.e. no automobiles)
• You must find your own route from checkpoint to checkpoint unless a mandatory route is specified in the race instructions.
• You must obey private property laws unless an area has been designated as "open" for race purposes
• You may not use a GPS; other navigation tools such as compasses, altimeters, and outside maps are permitted (and compasses are actually required!).
• You must be self-sufficient for the entire race, meaning the race organization doesn't provide aid stations with food or water. No support crews are permitted for this event, but the race organization will stage gear bins for you along the course.

If you're looking for enumerated rules in a more specific fashion, this PDF document outlines the official race rules.