Wollongong ( / ˈ w ʊ l ə ŋ ɡ ɒ ŋ / WUUL-ləng-gong) is a seaside city located in the Illawarra region of New South Wales, Australia. It lies on the narrow coastal strip between the Illawarra Escarpment and the Pacific Ocean, 82 kilometres (51 mi) south of Sydney. Wollongong has a population of 292,190, making it the third largest city in New South Wales after Sydney and Newcastle, and the ninth largest city in Australia.

The metropolitan area extends from Helensburgh in the north to Gerroa in the south, and is administered by the Wollongong, Shellharbour and Kiama councils. Geologically, the city is located in the south-eastern part of the Sydney basin, which extends from Newcastle to Nowra.

Wollongong is noted for its numerous surfing beaches, scenic lookouts and botanic gardens. It has two regional cathedrals, churches of many denominations and the Nan Tien Temple, one of the largest Buddhist temples in the southern hemisphere. Wollongong is a city with a long history of mining and industry, with coal mines, a steelworks and an industrial port. The city attracts numerous tourists each year, and is a regional centre for the South Coast fishing industry. The local University of Wollongong has around 22,000 students and is internationally recognised.

The name Wollongong is believed to mean "sound of the sea" in the local Aboriginal language, although other explanations have been offered, such as "great feast of fish", "hard ground near water", "song of the sea", "sound of the waves", "many snakes" and "five islands".