Would any existing site be adequate for questions about orienteering?
I've thought about Travel site, since it is mostly similar to tourism, but this is mainly oriented on tourist activities where you move on far distances...
I would ask orienteering questions in The Great Outdoors, as that site's charter covers
outdoor activities, excursions, and outdoorsmanship
of which I would include orienteering. The site has already handled questions about geocaching, waymarking, and letterboxing, which are in the same family of activities.
Alternatively, I could see a case for Sports. Orienteering is not necessarily competitive, but on the other hand we already have a bit of overlap between the two sites for questions about mountain biking or rock climbing, for example.