Social media is increasingly recognised as an important source of information about a wide range of issues, including nature-based tourism. We assess the current state of the academic literature to highlight what sources of data and methods are used, where and to assess which issues and what are the benefits and limitations of this novel source of data. Using a systematic quantitative literature review method, we identified 48 relevant publications mostly from Europe (18) and North America (10) as well as Asia (6), Oceania (5), Africa (4) or South America (3). Most research used Flickr images (36) and/or geodata (40), but studies also used Panoramio (10), Instagram (6), Twitter (3), OpenStreetMap (3), GPSies (2), Wikiloc (2), and Geocaching, Geograph, MapMyFitness and TripAdvisor (1 each) but not Facebook. Benefits include that data can be collected remotely, relatively simply and at low-cost, it complements other data sources, and can be effective in spatial and temporal analysis of visitation, to assess diverse cultural ecosystem services, evaluate visitor sentiments and assign economic values, with similar results to surveys and/or visitor counts. Limitations include fluctuations in popularity and access to data, that it only represents some visitors, areas and activities, demographic data is often limited, and there are important ethical issues. While more research from more locations is required, overall, social media is likely to be increasingly valuable for research and management of nature-based tourism.