Seasonal rainfall affects the outflow of the Pearl River, the largest river in southern China, causing brackish waters to extend into areas which for most of the year experience clear oceanic waters.

• 华南最大河流珠江所流出的河水，因受季节性的雨水影响，引致咸淡混合的水流，流入全年中大部分时间水质都是清澈的海洋。