24 Hour Adventure Race
Now here's where it really gets tough! The races in this category typically last 18-30 hours but 24 hours is by far the most common. After all there's a certain appeal to being able to say that you've done anything for 24 hours straight, especially something as mentally and physically challenging as adventure racing. It's a true life-list accomplishment to finish a 24 hour adventure race, and you will elicit looks of astonishment and awe from acquaintances and strangers when retelling the stories you'll be sure to have from one, similar in prestige to having completed an Ironman triathlon (though of course most of those wimpy triathletes will be quitting after 13 or 14 hours).
Of course you have to finish the race first before you can tell the stories, and doing so will be no easy task. Typical 24 hour adventure races will be held in remote areas with difficult terrain. Race directors, knowing that casual racers wouldn't dare sign up for a 24 hour long event, will unleash their sadistic side and come up with creative ways to make you suffer. Race legs will be long and grueling and you may be out on one leg for 8+ hours at a time without any access to additional food, water, or gear except that which you carry on your back. Race distances will often add up to 100 or more miles by the time you finish, with biking taking up the majority and trekking and paddling covering maybe 10-25 miles each.
That's in addition to any special challenges and the rope events of which there may be two or more. In a race of this length, the rope events may be intended to physically challenge the racers as well as thrill them. For example you may have a challenging traverse or have to ascend a rope. Orienteering will be difficult and you better hope your focus doesn't wane or you will end up miles off course. Mountain biking can be technical depending on the race location and long legs in the dark will test your nerves. You'd better be used to paddling for hours at a time too.
Speaking of dark, you will be spending an entire night racing in it which will vastly increase the difficulty of orienteering as you will often be off-trail and away from any man made objects. Your orienteering skills must be well honed in order to continue to find checkpoints by flashlight, especially as your body wears down - you won't be able to afford getting lost or taking wrong turns very often. And you'll have to get pretty close to the checkpoint flags to see them. You may have to fight off the sleep monsters or even consider taking a quick nap if you are struggling to maintain focus. Later in the race there may be periods of several hours where you don't see or hear another human being as teams can be quite spread out and usually some have dropped out after the first 15 or 16 hours of the race. Consequently you may have no idea what place you are in in the race and how many teams may have passed you unseen while taking slightly different routes.
Nutrition becomes a major factor in a race of this length. You will be burning calories much faster than you can replenish them and your body will protest this after a while. If you're not careful with what and when you eat and drink (and sometimes even if you are), gastrointestinal distress can result which you will just have to race through. Several factors can cause problems which I will go into in more detail on another page. Of course a little gastrointestinal distress is preferred if the alternative is dehydration or bonking if you aren't drinking or eating enough.
Another factor in 24 hour races is that sometimes it is required for your team to have a support crew (note that support crews are not necessarily forbidden in shorter races - you'll have to ask the race director). If not required, then it can be very helpful and a big time-saver. Support crews will transport your gear if there are any transition areas in the middle of the race. They can also organize everything so it's easy to find and prepare or buy food so you can have "real" food during the race, among other things.
It's never really possible to "master" a 24 hour race but if you've done a few and want the adventure of your life maybe a Multi-Day or Expedition Race is for you.