Its naturally sheltered and deep waters was to meet the requirements of British colonists attempting to establish a Far East maritime colony in that part of the world, thereby setting the stage for the eventual formation of Singapore as a successful independent state.
Keppel Harbour, by association with the rocky outcrop known as Batu Berlayar (and "Lot's Wife" in colonial times) has been speculated to be the site of Long Ya Men, one of two 14th-century settlements described by Chinese sojourner Wang Dayuan during his travels in Southeast Asia; it has not been systematically excavated to confirm this, however.
In the modern period, the harbour was first noticed in August 1819 by William Farquhar, who reported his discovery of a "new harbour" inhabited by orang laut ("sea people", the indigenous ethnic group made up of various tribes of seafarers in and around the straits of singapore) living in boats to Sir Stamford Raffles the following month.
It was also at this time that Captain Henry Keppel came to Singapore and helped to clear the Straits of pirates.
Whilst based at Singapore, he discovered the deep water anchorage that came to be called by his name.
Keppel first sailed to Singapore as a midshipman in 1832 and took part in the Naning (Malacca) expedition, and came again later in 1842 to help with the suppression of piracy in the Malay Archipelago.