Castor River North and South are two separate communities on either side of the mouth of Castor River. Castor River flows into the St. John Bay. The river was named by the French in 1735. Castor is the Latin word for "Beaver."

The Castor River area is scenic and rich in wildlife. The river flows west 100 km across the peninsula from the Long Range Mountain to its mouth in St. John's Bay. Castor River is one of the best salmon spawning and sea-trout rivers on the west coast of the island of Newfoundland. Visitors can enjoy excellent recreational fishing.

It is reported that the first settlers to Castor River were Jesse Humber and his family. In 1888, a Mr. Shearer of Nova Scotia moved into Castor River North and established a lobster cannery. By 1945, both communities began to separate with two different local committees, two schools, and two churches.

Community and business services for Castor River South include a K-12 school, Viking Trail Academy (located 27 kms north in Plum Point). Health care is provided in Port Saunders (44 kms south). A Canada Post Mail Box is available and a convenience store. Community, recreational and other business services are found in the towns of Port Saunders, Port au Choix and Hawkes Bay 44 kms to the south or Plum Point 27 kms to the north.