Sansum Narrows is a strait

Strait

A strait or straits is a narrow, typically navigable channel of water that connects two larger, navigable bodies of water. It most commonly refers to a channel of water that lies between two land masses, but it may also refer to a navigable channel through a body of water that is otherwise not...

 or channel between Vancouver Island

Vancouver Island

Vancouver Island is a large island in British Columbia, Canada. It is one of several North American locations named after George Vancouver, the British Royal Navy officer who explored the Pacific Northwest coast of North America between 1791 and 1794...

 (W) and Saltspring Island

Saltspring Island

Saltspring Island is one of the Gulf Islands in the Strait of Georgia between mainland British Columbia, Canada and Vancouver Island. It is the largest, the most populous, and the most frequently visited of the Gulf Islands...

 (E) in the Southern Gulf Islands

Gulf Islands

The Gulf Islands are the islands in the Strait of Georgia , between Vancouver Island and the mainland of British Columbia, Canada....

 region of British Columbia

British Columbia

British Columbia is the westernmost of Canada's provinces and is known for its natural beauty, as reflected in its Latin motto, Splendor sine occasu . Its name was chosen by Queen Victoria in 1858...

, Canada

Canada

Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...

. It is crossed by a BC Ferries

BC Ferries

British Columbia Ferry Services Inc. or BC Ferries is a de facto Crown Corporation that provides all major passenger and vehicle ferry services for coastal and island communities in the Canadian province of British Columbia...

 route from Crofton

Crofton, British Columbia

Crofton, British Columbia, Canada, is a small coastal town that is part of the District of North Cowichan on Vancouver Island in British Columbia. The population is estimated at 2,500 people...

 (just north of Duncan

Duncan, British Columbia

Duncan is a city on southern Vancouver Island in British Columbia, Canada.-History:The community is named after William Chalmers Duncan . He arrived in Victoria in May 1862, then in August of that year he was one of the party of a hundred settlers which Governor Douglas took to Cowichan Bay...

) to Vesuvius Bay on the northwestern shore of Saltspring. Its southern outlet adjoins Saanich Inlet

Saanich Inlet

Saanich Inlet is a body of salt water that lies between the Saanich Peninsula and the Malahat highlands of Vancouver Island, British Columbia, Canada. Located just northwest of Victoria, the inlet is 24 km long , has a surface area of 65 km2 , and its maximum depth is 225 m . Great...

 while its northern outlet is Houstoun Passage.

The powerline HVDC Vancouver-Island crosses Sansum Narrows in a 1900 metres long span.