Sansum Narrows is a strait or channel between Vancouver Island (W) and Saltspring Island (E) in the Southern Gulf Islands region of British Columbia, Canada. It is crossed by a BC Ferries route from Crofton (just north of Duncan) to Vesuvius Bay on the northwestern shore of Saltspring. Its southern outlet adjoins Saanich Inlet while its northern outlet is Houstoun Passage.
The powerline HVDC Vancouver-Island crosses Sansum Narrows in a 1900 metres long span.