Although outdoor recreation participation has been studied extensively, little research has come from less developed regions of the world. This paper examined outdoor recreation participation and its predictors in Istanbul, an increasingly urbanized and populated megacity, in Turkey. The results show that nearly half of the people interviewed in this study had claimed to visit a nature area at least once a week or more often, nearly three-quarters invested a travel time to these areas of between 30 min to 2 h, about two-thirds spent more than 2 h at the area, and about one-third was engaged in leisurely walking. The frequency of visits was almost the single predictor of travel time. Visit frequencies were predicted by the travel time and visit length. Activity type and traveling longer than 2 h predicted the length of visits. Recreational activity type was predicted by visit length and travel time. Socio-demographic variables were associated with only a few outdoor participation variables. The findings imply that the residents have limited contact with nature and limited opportunity to benefit from such interaction.