Sungai Pertama is one of the major tributaries of Sungai Perai, in Seberang Perai. It is erroneously labelled as Sungai Derhaka on Google Maps. The river gives its name to Kampung Pertama in Permatang Pauh. As we follow it upriver, there are no more signages, as the river changes into a canal that cuts through a flat rice-growing plain. While it is a tributary to Sungai Perai, Sungai Pertama itself is the trunk to other tributaries, one of which being Sungai Kubang Semang.