Brunei’s 161 kilometres of coastline zone contains the country's most productive ecosystem and most valuable onshore and offshore hydrocarbon deposits. Non-oil coastal resources are largely unexploited. Largely sandy with patches of mangrove swamps and mud rivers near river estuaries and sheltered bays is the Brunei coastline facing the open sea.

Complex are the surface and deep water currents along the coast due to oceanic tides, wind and water density interaction. Waves along the coast are usually between one to three metres high.

Less saline and relatively warm at 29.5 degrees Celsius are the coastal waters, enriched by land nutrients caried by river waters to support marine life, making coastal waters rich fishing grounds. Some 500 species of fish and 12 shrimp and prawn species have been identified.

The mangrove-fringed Brunei, Temburong and Limbang River estuaries have high organic contents and contribute to the richness of Brunei coastal fisheries. Shrimp is abundant and peak catches are made from February to April after the northeast monsoon rainy season.

Five hundred species of fish and insects have been reported in Brunei waters as well as 12 species of shrimp.

More than 85 per cent of Brunei's population live in the coastal areas. The Brunei-Muara district is the most populated. Efforts are being undertaken to minimise pollution and damages to the environment and ecosystem as the country accelerates industrialisation and urbanisation.