Mercia TREC Club: English club that practices TREC, a competition that is a combination of orienteering on horseback, and maintaining set speeds (normally trot or walk).
Michigan Competitive Mounted Orienteering: Sport, membership, and ride information.
National Association of Competitive Mounted Orienteering: A non-profit organization offering information on the objectives of the sport, membership, ride calendar, ride results, chatroom, newsletters, and links.
TREC UK: Information about the sport of TREC, which includes mounted orienteering, and discussion forum.