Singapore has a lot of traffic sailing through our waters. These ships will always end up dumping rubbish or waste into the water. Another factor is that our waters are straits so the waste does not really get washed away into the ocean. Australia is surrounded by ocean.

The murky appearance of Singapore's waters is primarily caused by suspended sediment and silt, rather than industrial pollution. Historically, in the 1960s, visibility was quite high (up to 10 meters), but decades of intensive land reclamation and coastal development have stirred up the seabed. Constant dredging to maintain Singapore’s status as one of the world's busiest container ports keeps fine particles of clay and sand suspended in the water column, which scatters light and reduces visibility to about 1.5 to 3 meters. Additionally, the Malacca Strait is a naturally high-sediment area due to river runoff from Sumatra and the Malay Peninsula, which carries organic matter and silt into the surrounding seas. Heavy tropical downpours also contribute by washing soil from the land into the drainage systems and out to sea. Despite the "brownish" or "murky" look, Singapore's marine ecosystem remains surprisingly biodiverse, with many coral reefs and sea grass meadows surviving by adapting to lower light levels. The government also utilizes "silt curtains" during construction to mitigate further cloudiness and protect the remaining natural reefs.