Brunswick River rises on the eastern slopes of Mount Jerusalem, at Palmwoods, near Uki, and flows generally east southeast, before reaching its mouth at the Coral Sea of the South Pacific Ocean, at Brunswick Heads.

The river descends 142 metres (466 ft) over its 34 kilometres (21 mi) course;[3] through the towns of Mullumbimby and Brunswick Heads.

This lake becomes a popular swimming hole in the summer months and is used by naturists who come down from Tyagrah Beach.

Marshalls Creek also connects to a canal in Ocean Shores North and South Golden Beach.

The south arm of the river, called Simpsons Creek, flows through Brunswick Heads, Bayside and Tyagarah.