Which ocean lies between Africa and Australia?

Look at a globe from above the Indian subcontinent and the geometry becomes obvious: East Africa forms the western shore, Australia the eastern one, Asia closes the basin to the north, and the Southern Ocean opens it to the south. That enclosed northern edge is what makes this ocean behave differently from the others. Because Asia heats and cools far more than the sea does, the winds over the northern basin reverse with the seasons, blowing from the southwest in summer and the northeast in winter. Sailors learned to ride that rhythm long before the age of European exploration, which is why trading networks linking Arabia, Persia, Gujarat, the Swahili coast and the Indonesian archipelago were flourishing centuries earlier than the Atlantic equivalents. The ocean's name in several languages still reflects that Indian-centred trade, and its currents and cyclone seasons remain governed by the same monsoon cycle.

The Indian Ocean is the only major ocean whose surface currents reverse direction seasonally in its northern half.