Despite sustainability being a key concern in tourism studies, surprisingly few studies exist on international visitors' perceptions of destination sustainability. One of the difficulties in assessing studies of sustainability is that the concept is used in an inconsistent manner. With a tourism strategy that focuses on tourism growth that is productive, sustainable and inclusive, the tourism industry in New Zealand has put sustainability at the core of its destination strategy. However, there is little evidence to support whether international tourists are concerned about destination sustainability and if they are, which facets matter the most to them. These are the two research questions that this study attempts to answer. UGC from Trip Advisor and Expedia was analysed using keywords representing different facets of economic, socio-cultural and environmental sustainability for the Canterbury region. Based on 67181 online comments, the findings showed that price was the most pressing economic sustainability issue, while friendliness of staff and locals was the most mentioned socio-cultural sustainability issue. Recycling was among the words that were most often mentioned about hotels in online comments. Implications for destination management are offered.