Call up sports reporters directly and tell them about the event. Be ready with a short explanation of: 1. what orienteering is (using buzz words that will catch their attention - exciting, adventure, etc), and 2. a compelling reason WHY they should run with the story. This is most important - journalists get hundreds of press releases and story requests per day. WHY is your story remarkable and worth taking the time to write?
Then email a
properly formatted press release if they ask for one, or even better is just an email with the event details. Be sure to include a good, short blurb on what orienteering is, some good quotes, etc. Some reporters may just copy/paste, or change only a few words from what you wrote in your email, so that way you control the message. Include a couple of good photos in the email - don't send them to an external source for those (most won't bother clicking on links).