== Mud volleyball == 

 Well, after looking at the links, I am even more inclined to say that it is a non-notable version of volleyball.  It's simply the same thing as volleyball (indoor/outdoor), played in mud.  It also looks like it is only played during a fund-raiser.  There is no national organization and it's not an actual variant of volleyball with a rules body and the like.  Hope that helps.  Cheers,