Colac is a small city in the Western District of Victoria, Australia, approximately 150 kilometres south-west of Melbourne on the southern shore of Lake Colac.

The Princes Highway (part of Australia’s circumnavigational Highway 1) runs through the city and forms its main street, Murray Street. The highway runs west toward Camperdown and east to Geelong and beyond to Melbourne. Several secondary sealed roads including the C161, C155 and C154 run south toward Apollo Bay and the coastal tourism areas of the Otway Ranges Great Ocean Road, The Twelve Apostles and the Shipwreck Coast. The Colac-Ballarat Road runs north connecting Colac to Ballarat via Cressy.