Its drainage basin is 3,328 square kilometres (1,285 sq mi) in size.

[3] The total length of the Squamish River is approximately 80 kilometres (50 mi).

The Squamish River drains a complex of basins in the Coast Mountains just north of Vancouver.

Its flows generally south to the head of Howe Sound[4] where the town of Squamish is located.

The Skwelwil'em Squamish Estuary Wildlife Management Area is located at the river mouth.