<human>:  How many people are involved in orienteering?
<bot>: That’s hard to say. There are many different types of orienteering. I think there are over 300,000 registered participants in the United States alone. The most common type of orienteering is called trail running, where participants run through a series of checkpoints while navigating their way through a forest, desert, or other type of terrain. Trail running events are often organized as part of a larger event, such as a triathlon or a road race.