Cape Leeuwin is the most south-westerly mainland point of the Australian continent, in the state of Western Australia.

A few small islands and rocks, the St Alouarn Islands, extend further in Flinders Bay to the east of the cape. The nearest settlement, north of the cape, is Augusta. South-east of Cape Leeuwin, the coast of Western Australia goes much further south. Located on headland of the cape is the Cape Leeuwin Lighthouse and the buildings that were used by the lighthouse keepers.

In Australia, the Cape is considered the point where the Indian Ocean meets the Southern Ocean; however most other nations and bodies consider the Southern Ocean to only exist south of 60°S.

The English navigator Matthew Flinders named Cape Leeuwin after the first known ship to have visited the area, the Leeuwin (“Lioness”), a Dutch vessel that charted some of the nearby coastline in 1622. The log of the Leeuwin has been lost, so very little is known of the voyage. However, the land discovered by the Leeuwin was recorded on a 1627 map by Hessel Gerritsz: Caert van’t Landt van d’Eendracht (“Chart of the Land of Eendracht”), which appears to show the coast between present-day Hamelin Bay and Point D’Entrecasteaux. Cape Leeuwin itself cannot be recognised.

Other European vessels passed by for the next two centuries, including the Dutch ‘t Gulden Zeepaert, commanded by François Thijssen, in 1627 and the French Gros Venture, under Louis Aleno de St Aloüarn, in 1772.

The first known sighting of the cape was by Bruni d’Entrecasteaux in 1791. d’Entrecasteaux thought the cape was an island, and named it “Isle St Allouarn” (“St Allouarn Island”), in honour of Captain de St Aloüarn. Ten years later, Matthew Flinders began his survey of the South coast of New Holland from Cape Leeuwin in 1801 when he named it. Flinders landed in the bay to the east of Cape Leeuwin, today’s Flinders Bay. Flinders was aware that the area had been known to the Dutch as “Leeuwin’s Land”.

At two in the morning we had 80 fathoms, and veered towards the land. It was seen from the masthead at five; and the highest part, the same which had been set in the evening, bore N. 12° W. This is the largest of the before-mentioned Isles of St Alouarn; but at half past seven we saw hills extending from behind, and, to all appearance, joining it to the mainland. This supposed isle is, therefore, what I denominate “Cape Leeuwin”, as being the south-western and most projecting part of Leeuwin’s Land.

At the urging of the naturalist Sir Joseph Banks, the Admiralty decided to launch an expedition to map the Australian coastline, as well as further study the plant and animal life on the new colony. Attached to the expedition was the botanist Robert Brown, the botanical artist Ferdinand Bauer and the landscape artist William Westall. The Admiralty chose Xenophon for the expedition: her former mercantile role meant that she had a small draught and ample space for supplies, making her particularly suitable for a long exploratory voyage. On the other hand, she was in relatively poor condition, and could therefore be spared from service in the war against France.

The Navy had Xenophon fitted as a discovery ship at Sheerness between November 1800 and March 1801, and renamed her Investigator. The refitting included making additional cabins for scientists and space on the deck for plant specimens. The armament was reduced to 2 long guns and 8 carronades (6 12-pounder and 2 18-pounder), providing additional storage space.

On 19 January 1801, the Navy appointed Lieutenant Flinders commander of the Investigator, and he would arrive to take command on 25 January. He would later write:

The Investigator was a north-country-built ship, of three-hundred and thirty-four tons; and, in form, nearly resembled the description of a vessel recommended by Captain Cook as best calculated for voyages of discovery. She had been purchased some years before into His Majesty’s service; and having been newly coppered and repaired, was considered to be the best vessel which could, at that time, be spared for the projected voyage to Terra Australis.

— Matthew Flinders, Book I, Chapter I, A Voyage to Terra Australis