The Great Ocean Road, officially designated as the B100, begins at Torquay and travels 243 kilometres westward to finish at Allansford near Warrnambool, the largest city along the road. The road is two lane (one in each direction), with the majority covered by an 80 kilometre per hour speed limit.

The road is considered a tourist attraction in the area, in which much of the road hugs coastline affectionately known as the Shipwreck Coast, providing visibility of Bass Strait and the Southern Ocean. The road traverses rainforests, as well as beaches and cliffs composed of limestone and sandstone, which is susceptible to erosion. The road travels via Anglesea, Lorne, Apollo Bay, and Port Campbell, the latter being notable for its natural limestone and sandstone rock formations including Loch Ard Gorge, The Grotto, London Arch and The Twelve Apostles.

The city of Geelong, close to Torquay, experiences great benefit from Australian and international visitors to the road; with Geelong Otway Tourism affirming it as an invaluable asset. The Royal Automobile Club of Victoria (RACV) listed the road as the state's top tourism experience in its Victoria 101 survey, based on spots recommended by members and the public on what they would recommend to visitors.

Besides standard vehicular travel, a 45 kilometre section between Lorne and Apollo Bay is used for the annual Great Ocean Road Marathon, first started in 2005. As of 2010[update], the marathon record of two hours, 29 minutes and 41 seconds is held by Geelong resident Mark Tucker.

The Great Ocean Road was first planned in 1864, when chairman of the Country Roads Board William Calder asked the State War Council for funds be provided for returned soldiers to work on roads in sparsely populated areas in the Western district. By the time of World War I, the rugged south-west coast of Victoria was accessible only by sea or rough bush track. Besides being dedicated as a memorial, it was also envisioned that the road would connect isolated settlements on the coast, and become a vital transport link for the timber industry and tourism.

Surveying for the road, tentatively titled the South Coast Road, started in 1918 - with the road suggested to travel from Barwon Heads, follow the coast west around Cape Otway, and end near Warrnambool. In 1918, the Great Ocean Road Trust was formed as a private company, under the helm of president Howard Hitchcock. The company managed to secure £81,000 in capital from private subscription and borrowing, with Hitchcock himself contributing £3000. Money would be repaid by charging drivers a toll until the debt was cleared, and the road would then be gifted to the state.

Construction on the road began on 19 September 1919, built by approximately 3,000 returned servicemen as a war memorial for fellow servicemen who had been killed in World War I. An advance survey team progressed through dense wilderness at approximately 3 kilometres a month. Construction was done by hand; using explosives, pick and shovel, wheel barrows, and some small machinery, and was at times perilous, with several workers killed on the job; the final sections along steep coastal mountains being the most difficult to work on. Anecdotal evidence from ABC archives in 1982 suggested workers would rest detonators on their knees during travel, as it was the softest ride for them.

The soldiers were paid 10 shillings and sixpence for eight hours per day, also working a half-day on Saturdays. They used tents for accommodation throughout, and made use of a communal dining marquee and kitchen; food costing up to 10 shillings a week. Despite the difficulty involved in constructing the road, the workers had access to a piano, gramophone, games, newspapers and magazines at the camps. Additionally, in 1924, the steamboat Casino became stranded near Cape Patton after hitting a reef, forcing it to jettison 500 barrels of beer and 120 cases of spirits. The workers obtained the cargo, resulting in an unscheduled two week long drinking break.

On 18 March 1922 the section from Eastern View to Lorne was officially opened with celebrations. However it was then closed from 10 May 1922 for further work; opening again on 21 December along with tolls to recoup construction costs. The charge, payable at Eastern View, was two shillings for motor cars, and 10 shillings for wagons with more than two horses.

In November 1932, the section from Lorne to Apollo Bay was finished, bringing the road to completion. The road was officially opened with Victoria's Lieutenant-Governor Sir William Irvine holding a ceremony near Lorne's Grand Pacific Hotel, and the road subsequently being acknowledged as the world's largest war memorial. At the time, newspaper The Age commented - "In the face of almost insurmountable odds, the Great Ocean Road has materialised from a dream or 'wild-cat scheme', as many dubbed it, into concrete reality". Hitchcock had however died of heart disease on 22 August 1932, before the road was completed, though his car was driven behind the governor's in the procession along the road during the opening ceremony. A memorial was constructed in Hitchcock's name on the road at Mount Defiance, near Lorne, and he is still affectionately considered the Father of the Road.