Positioned on the west side of Pelumpong Point's entrance, PMB is sparsely populated, with the forest canopy, which becomes denser toward the eastern end, reaching heights of 60 to 100 feet (18 to 30 m).

[6] Muara Port, a sheltered area between PMB and the western coast, is 3 miles long and 400 to 800 yards wide, with depths ranging from 3 to 5½ fathoms on a mud bottom.

[7] Anson Passage, to the north of PMB, is suitable only for small vessels with a draft of less than 9 feet due to its 7-foot depth at low-water spring tides.

In July 1842, James Brooke's ship, the Royalist, anchored off PMB, a low, sandy island near the mouth of the Brunei River.

Situated along the northwestern coast, the island served as a link between the more dramatic coastal landscapes north of the city and the less scenic lowland shores to the south.

[12]PMB was strategically significant during Operation Oboe 6 in 1945, with anti-aircraft positions near Cape Sapo and Brooketon, which overlooked Yellow Beach.

While the Japanese positions on the island were not as heavily fortified as those on Tarakan,[13] their coastal defences included artillery and anti-aircraft guns, capable of hindering landings, especially if the enemy chose to fight to the death, despite being understrength and poorly supplied.

[14] As part of a coordinated divisional effort, the 20th Brigade, under the command of Brigadier Victor Windeyer, was tasked with securing PMB during Operation Oboe 6.

In the second phase, from 7 June to Z Day, the focus shifted to supporting minesweeping operations, convoy protection, and targeting specific enemy positions, including those on PMB.

Additionally, naval minesweeping operations cleared a channel into Brunei Bay, while the Cruiser Covering Group conducted bombardments to mark the approach to White Beach.

On 15 August 1945, when Japan accepted the terms of the Potsdam Declaration, marking the end of offensive operations, the ship remained at PMB until September.

[19] In 1967, a temporary site at PMB was selected to serve as the Government Marine Base, with the suggestion to establish a veterinary quarantine station on the island.

Phase 1 of the refinery, covering 260 hectares (640 acres), was scheduled for completion in 2015 and is set to produce gasoline, diesel, jet fuel, paraxylene, and benzene, generating 800 local jobs.

[31] In order to consolidate all offshore oil and gas exploration and production support activities, an Integrated Marine Supply Base (IMSB) has been established on an 11-hectare plot of land on PMB's southern shoreline.

[32] Anson International has agreed to open the island as Brunei's first commercial integrated marine maintenance and decommissioning yard (MMDY) to first meet local needs before expanding into other regions.

[33] The 16 hectares (40 acres)[34] integrated yard that will be built as part of the deal, which was signed on 29 June 2022, at the MoFE, will act as the anchor facility for the Brunei Darussalam Maritime Cluster (BDMC).