Pulau Tekong is the largest of Singapore's outlying islands with an area of 24.43 km2, and the island is still expanding due to land reclamation works on its southern and northwestern coasts which will eventually subsume many of its surrounding small islets, including Pulau Tekong Kechil.
Pulau Tekong is found off Singapore's northeastern coast, east of Pulau Ubin. Geographically, it is nearer to Johor, Malaysia than the Singapore main island itself. The Pulau Tekong Reservoir is also on the island.
Today, Pulau Tekong is used exclusively as a training base for various Singapore Army Units. Home to the Basic Military Training Centre (BMTC), this is also where young Singaporean males are conscripted into National Service. The School of Infantry Specialists (SISPEC), which was situated Rocky Hill Camp, relocated to a new campus at Pasir Laba Camp in December 2005. A new training area built by Combat Engineers, called Sanyongkong Field Camp, has been completed on the reclaimed land south of Dogra Bridge and it will be used to train battalions of the Infantry and Guards. It also provides habitat to some wild animals that are rarely seen on main island Singapore such as the leopard cat, Sunda slow loris and Sunda pangolin. The expanded Pulau Tekong will massively replace all training grounds on main island Singapore.
The National Biodiversity Centre and National Parks Board (NParks) will be conducting coastal protection and restoration works along the coastline of the island which suffers from coastal erosion. A study NParks conducted in 2006 found that 1.65 km of the north-eastern shore is affected the most. The coastal erosion poses a threat to the 92 ha of mangroves in Pulau Tekong which is one of the largest remaining mangrove areas in Singapore with a mature and undisturbed habitat. Ecologists point out that the island is extremely rich in biodiversity and resident to some rare or endangered species.