The G21 region (map) is located in south-western Victoria, between 75 and 160 kilometres from Melbourne. The G21 – Geelong Region Alliance includes Colac Otway Shire, Golden Plains Shire, the City of Greater Geelong, the Borough of Queenscliffe and Surf Coast Shire. The region has a population of over 315,000, which is projected to increase to approximately 500,000 by 2050.

The G21 region is a rural, residential and resort area with some industrial and commercial land use. The region encompasses a total land area of nearly 9000 square kilometres, including significant areas of State Forest and National Park. Much of the rural area is used for timber-getting, farming, grazing, cropping, dairying, mining and viticulture. Tourism is an important industry, especially in the southern section along the Great Ocean Road and the Bellarine Peninsula.

Geelong is the largest city and major population centre of the G21 region. Other major towns in the region include Colac, the coastal towns of Anglesea, Apollo Bay, Lorne, Ocean Grove and Torquay and the inland rural centres of Bannockburn and Winchelsea.

Historically, Geelong was the commercial centre for the fine wool growing, manufacturing and export trade for south-east Australia. As such, it had significant textile-related industries, include wool scouring and carpet making. It also became a major manufacturing centre as home to large industries such as Ford, Alcoa and Shell. However, partly in response to international economic pressure on big manufacturing, the region has more recently begun broadening its economy towards advanced education, industrial and scientific research, health and tourism industries.