Thirlmere is a small semi-rural town in the Macarthur Region of New South Wales, Australia, in Wollondilly Shire. Popularly known for its railway origins, the town is located 89 km south west of Sydney (about a 60-minute drive), one third of the distance from Sydney to Canberra. At the 2016 census, Thirlmere had a population of 4,046. Thirlmere was previously known as Village of Thirlmere and was originally named after Thirlmere in England.