Obstacle Course Race
This is more fun than a sport but does include many diciplines and requires very fast reactions to get the shots as they happen. Logisitics, planning and navigation all come into events like this.
I've shot for Born Survivor and Total Warrior mainly, also other smaller events around the country.
Photographing mud is the most fun I have, there's plenty about which can make a big mess, especally when the competitors jump into it!