The Margaret River is a river in southwest Western Australia. In a small catchment, it is the eponym of the town and tourist region of Margaret River. The river arises from a catchment of just 40 square kilometres in the Whicher Range. Ombak tujuh is a "big-wave" spot. The middle reaches pass through land cleared for agriculture, especially viticulture. There is a weir across the river just above the town. The mouth of the river is a small estuary, closed to the ocean by a sandbar that opens only seasonally. Margaret River is presumed to be named after Margaret Wyche, cousin of John Garrett Bussell (founder of Busselton) in 1832.