His Majesty's Armed Survey Vessel Lady Nelson was commissioned in 1799 to survey the coast of Australia. At the time large parts of the Australian coast were unmapped and Britain had claimed only part of the continent. The British Government were concerned that, in the event of settlers of another European power becoming established in Australia, any future conflict in Europe would lead to a widening of the conflict into the southern hemisphere to the detriment of the trade that Britain sought to develop. It was against this background that Lady Nelson was chosen to survey and establish sovereignty over strategic parts of the continent.

Port Phillip or Port Phillip Bay is a horsehead-shaped enclosed bay on the central coast of southern Victoria, Australia. The bay opens into the Bass Strait via a short, narrow channel known as The Rip, and is completely surrounded by localities of Victoria's two largest cities — metropolitan Greater Melbourne in the bay's main eastern portion north of the Mornington Peninsula, and the city of Greater Geelong in the much smaller western portion north of the Bellarine Peninsula. Geographically, the bay covers 1,930 km2 (750 sq mi) and the shore stretches roughly 264 km (164 mi), with the volume of water around 25 km3 (6.0 cu mi). Most of the bay is navigable, although it is extremely shallow for its size — the deepest portion is only 24 m (79 ft) and half the bay is shallower than 8 m (26 ft). Its waters and coast are home to seals, whales, dolphins, corals and many kinds of seabirds and migratory waders.