Adventure Racing is more than just a sport: It's an experience.  It can be best defined as a race lasting from 3 hours to 9 days where in teams of two to four you navigate your way from checkpoint to checkpoint in the mode as dictated by the race director.  Typically this includes mountain biking, running, and kayaking, but every so-often crazy things happen, like running with kayaks on your shoulder.  You sleep when you need to, eat only what you can carry in your pack, and the routes are not marked.  The maps with the race checkpoints are typically revealed right before the race, and then teams are to choose and navigate the fastest route between the checkpoints.  The key to a successful adventure racing team is good team dynamics, navigation, accepting mistakes, and checking your egos at the door.  Check out this Eco-Challenge promo to learn more: