The Pulau Semakau, south of Pulau Bukom, covers a total area of 350 hectares (approximately the size of Sentosa). It is a landfill formed by joining Pulau Semakau to Pulau Sakeng with rock bunds and it is one of the largest and the first to be located so far offshore. The Transfer station now sits on the former Pulau Sakeng. Besides the landfill, there are unspoilt mangroves, vast seagrass meadows, coral reefs, sandy shores. Entry to the island is only with designated interest groups. Marine life of Pulau Semakau includes the common sea star (Archaster typicus), seagrasses, sandfish sea cucumber (Holothuria scabra), upside-down jellyfish (Cassiopea sp.), long-spine sea urchins (Diadema setosum), and much, much more.

Pulau Sakeng used to be the site of a sea village (kampong laut) inclusive of several shops catering to islanders and visitors. The village was built largely on stilts over a reef flat. Most of the villagers were subsistence fishers, making a living off the nearby reefs.

Pulau Semakau was home to a slightly smaller community, and even boasted a football at one end of the village.

Semakau Landfill was commissioned in April 99 with the closure of Lorong Halus Dumping Ground (the last remaining landfill on Singapore's mainland) on 31st March 1999. All non-incinerable refuse such as construction and renovation debris and ash from incineration plants are now disposed of at the Landfill. On 16 July 2005, Pulau Semakau was opened for nature-related recreational activities. Intertidal walks

Semakau intertidal tour is available with the Raffles Museum of Biodiversity Research. We joined their first Semakau walk for the year 2007, we were in the clown fish group led by Ron and July, and we really enjoy it. In fact, incorporated into this tour is the Landfill tour by NEA.