Here s an outline of the issues. Conflict can be defined as 'goal interference that is attributed to another's behaviour'. Social conflict between walkers and mountain bikers is topical today, but conflict has existed between many outdoor groups for decades. More specifically, conflict exists between individuals. As always, generalisations about groups of people should be scrutinised regularly and used with due caution.
Some recreational goals are intrinsically incompatible.
For example, a snorkeller hoping to take photos of mature crayfish is unlikely to find much satisfaction in an area frequented by extractive divers. A walker listening for bird call will more than likely find the sound of a trail bike unacceptable. Frustrated fly-fishers frown upon friendly rafters and kayakers. Also, some goals such as seeking solitude preclude the presence of others even of like-mind. Similarly a skier looking for un-tracked powder may be in conflict with other skiers whose goals are exactly the same.