Jakarta Bay

Jakarta Bay sheltered the sea approaches to Jayakarta and, from 1619, the Dutch East India Company's city of Batavia. Its offshore islands formed part of the port's working machinery. In 1610 the company obtained permission from the prince of Jayakarta to use Onrust; by 1615 the island had shipbuilding facilities, warehouses and a small hospital for sailors. Jan Pieterszoon Coen made it a forward defensive position in 1618, amid rivalry with Banten and the English.

Onrust's fortifications grew from a square fort built in 1656 into a five-bastioned work in 1671. Windmills and workshops served the vessels that connected Batavia with the company's Asian trading network. Company employees and enslaved labourers lived on the island, maintaining a naval establishment separated by water from the city. The same exposed approaches became a liability during the wars with Britain: British forces occupied Onrust and destroyed its buildings in 1800, then blockaded Batavia. Ship repair, fortified islands and the vulnerability of the anchorage shaped the bay's early modern history.