Question: A British officer of the Royal Navy best known for his 1791-95 expedition first charted what in 1793?

Context paragraphs:
Zarembo Island: Zarembo Island is an island in the Alexander Archipelago of southeastern Alaska, United States.  It lies directly south of Mitkof Island and northwest of Etolin Island.  To the northwest is Kupreanof Island and to the southwest is Prince of Wales Island.  It has a land area of 183.14 sqmi , making it the 34th largest island in the United States.  It has no permanent resident population.  It was first charted in 1793 by James Johnstone, one of George Vancouver’s officers during his 1791-95 expedition.  He only charted its north, west, and south coasts, not realizing it was an island.  The island is named after Dionizy Zaremba, a Polish employee of the Russian American Company and explorer of Alaska.  Usually known as Dionysius Zarembo, he was Commander of the RAC ship "Chichagof" during the foundation of the Redoubt San Dionisio, named for his name-saint, a fortification at present-day Wrangell which was established to forestall encroachment of the Stikine region by the Hudson's Bay Company.

George Vancouver: Captain George Vancouver (22 June 1757 – 10 May 1798) was a British officer of the Royal Navy, best known for his 1791–95 expedition, which explored and charted North America's northwestern Pacific Coast regions, including the coasts of contemporary Alaska, British Columbia, Washington, and Oregon.  He also explored the Hawaiian Islands and the southwest coast of Australia.

Cousins Inlet: Cousins Inlet is a fjord in the Central Coast region of the Canadian province of British Columbia.  It extends north from Fisher Channel.  At its head is the community of Ocean Falls.  It was first charted in 1793 by George Vancouver and , during their 1791-95 expedition to survey the Pacific Northwest.

Pooley Island: Pooley Island is an island in the North Coast region of British Columbia, Canada.  To its west and southwest is Roderick Island, to its east Mathieson Channel.  James Johnstone, one of George Vancouver's lieutenants during his 1791-95 expedition, first charted its north and east coasts in 1793.  The island was later named after Charles Edward Pooley.  Son of world-famous Sea Captain Kate Pooley, first ever female to successfully charter the islands of British Columbia's Coast.  While successfully fending off 4 pirate ships, one containing Captain Jack Sparrow.  Yes, she is amazing.

Sarah Island (British Columbia): Sarah Island is an island in the North Coast of British Columbia, Canada.  It is separated from Princess Royal Island to its west by Tolmie Channel, and from Roderick Island to its east by Finlayson Channel.  Its east coast was first charted in 1793 by James Johnstone, one of George Vancouver's lieutenants during his 1791-95 expedition.

Etolin Island: Etolin Island is an island in the Alexander Archipelago of southeastern Alaska, United States at .  It is between Prince of Wales Island, to its west, and the Alaska mainland, to its east.  It is southwest of Wrangell Island.  It was first charted in 1793 by James Johnstone, one of George Vancouver's officers during his 1791-95 expedition.  He only charted its southwest and east coasts, not realizing it was an island.  It was originally named Duke of York Island but was renamed by the United States after the Alaska Purchase.  It is named after Adolf Etolin, governor of the Russian American colonies from 1840 to 1845.

Pearse Island: Pearse Island is an island in western British Columbia, Canada, in the Portland Inlet, an inlet of the Pacific Ocean.  The island was first charted in 1793 by George Vancouver during his 1791-95 expedition.  It was named by George Henry Richards, captain of "HMS Plumper", circa 1860, in honour of William Alfred Rombulow Pearse of the Royal Navy, who had been commander of "HMS Alert".

Briggs Inlet: Briggs Inlet is a fjord in the North Coast region of the Canadian province of British Columbia.  It lies between the Florence and Coldwell Peninsulas.  It was named by H.D. Parizeau of the Hydrographic Service after Thomas S. Briggs, a former agent with the Canadian Pacific Navigation Company.  It was first charted in 1793 by , one of George Vancouver's lieutenants during his 1791-95 expedition.

Fisher Channel: Fisher Channel is a channel in the Central Coast region of the Canadian province of British Columbia.  To its west are Hunter and Denny Islands, to its east King Island.  It was first charted in 1793 by George Vancouver during his 1791-95 expedition.  He named it "Fisher’s Channel" after "a much-respected friend".

Cascade Inlet: Cascade Inlet is a fjord in the North Coast region of the Canadian province of British Columbia.  It extends northwest from Dean Channel.  It was first charted in 1793 by George Vancouver and during their 1791-95 expedition.  Vancouver named it “Cascade Channel” due to the great number of waterfalls he saw along its sides when he first explored the inlet.

Supporting paragraphs: Cascade Inlet George Vancouver
Answer: Cascade Inlet