Frederick Arm is an inlet

Inlet

An inlet is a narrow body of water between islands or leading inland from a larger body of water, often leading to an enclosed body of water, such as a sound, bay, lagoon or marsh. In sea coasts an inlet usually refers to the actual connection between a bay and the ocean and is often called an...

 on the South Coast of British Columbia

British Columbia Coast

The British Columbia Coast or BC Coast is Canada's western continental coastline on the Pacific Ocean. The usage is synonymous with the term West Coast of Canada....

, extending north from Cordero Channel

Cordero Channel

Cordero Channel is a strait in British Columbia, Canada, located between the mainland and Vancouver Island, among the Discovery Islands north of the Strait of Georgia. Cordero Channel runs north of Sonora Island, East Thurlow Island, and part of West Thurlow Island. Its eastern end connects to the...

 between Lougborough

Loughborough Inlet

Loughborough Inlet is one of the lesser principal inlets of the British Columbia Coast. It penetrates the Coast Mountains on the north side of the Discovery Islands archipelago, running about from its head at the mouth of the Stafford River to Chancellor Channel and Cordero Channel, which are on...

 and Bute Inlet

Bute Inlet

Bute Inlet is one of the principal inlets of the British Columbia Coast. It is 80 km long from its head at the mouths of the Homathko and Southgate Rivers to the continental headlands at its mouth, where it is nearly blocked by Stuart Island, and it averages about 4 km in width...

s.

Originally conferred with the name Ensenada del Estero by Spanish explorers Galiano and Valdes, its current name was given c.1864 by Captain Pender, RN (namesake of Pender Island

Pender Island

Pender Island is one of the Southern Gulf Islands located in the Gulf of Georgia, British Columbia, Canada. Pender Island is approximately in area and is home to about 2,500 permanent residents, as well as a large seasonal population...

), after Staff Commander Frederick John Owen Evans

Frederick John Owen Evans

Sir Frederick John Owen Evans , was a hydrographer.Ecans, son of John Evans, master R.N., was born on 9 March 1815. He entered the navy as a second-class volunteer in 1828...

, naval hydrographer, British Admiralty. The name Estero survives in the vicinity in the form of Estero Basin, which lies between the north end of Frederick Arm and the south end of Bute Inlet and Estero Peak, on the south side of Estero Basin. "Estero" means "lagoon", while Ensenada de Estero means "Bay of the Lagoon". San Josef Mountain in the same vicinity was named for the San Josef

HMS San Josef

HMS San Josef was a 114-gun first rate ship of the line of the Royal Navy. She was captured from the Spanish Navy at the Battle of Cape St Vincent on 14 February 1797...

, a prize Spanish frigate that was captured by the Royal Navy and became part of the fleet

Frederick Arm should not be confused with Frederick Sound

Frederick Sound (Canada)

Frederick Sound is a sound in the Central Coast of British Columbia, Canada. it is the south arm and largest sidewater of Seymour Inlet and along with that inlet was named in honour of Frederick Seymour, second governor of the Colony of British Columbia. Frederick Sound has two inlets, one named...

, which is a sidewater of Seymour Inlet

Seymour Inlet

Seymour Inlet is one of the lesser traveled of the principal inlets of the British Columbia Coast. Unlike larger inlets such as Knight or Bute, it is not flanked by mountains but by relatively low, but still rugged, coastal hill-country and forms a maze of complex, narrow waterways and tidal pools...

 in the area to the north of Queen Charlotte Strait

Queen Charlotte Strait

Queen Charlotte Strait is a strait between Vancouver Island and the mainland of British Columbia, Canada. It connects Queen Charlotte Sound with Johnstone Strait, Discovery Passage and then to the Strait of Georgia and Puget Sound...

.