Vancouver had already sailed with Cook on his second southern voyage; he had accompanied him on the Discovery  during his last voyage. He therefore knew something of the coast of North-West America. "On the 15th of December 1790, I had the honour of receiving my commission as commander of His Majesty's sloop the Discovery, then lying at Deptford, where I joined her," says Vancouver. "Lieutenant Broughton having been selected as a proper officer to command the Chatham, he was accordingly appointed. At day dawn on Friday the 1st of April we took a long farewell of our native shores. Having no particular route to the Pacific Ocean pointed out in my instructions, I did not hesitate to prefer the passage by way of the Cape of Good Hope."

In boisterous weather Vancouver rounded the Cape, made some discoveries on the southern coast of New Holland, surveyed part of the New Zealand coast, discovered Chatham Island, and on 17th April 1792 he fell in with the coast of New Albion. It was blowing and raining hard when the coast, soon after to be part of the United States of America, was sighted by the captains and crews of the Discovery  and Chatham. Amid gales of wind and torrents of rain they coasted along the rocky and precipitous shores on which the surf broke with a dull roar. It was dangerous enough work coasting along this unsurveyed coast, full of sunken rocks on which the sea broke with great violence. Soon they were at Cape Blanco (discovered by Martin D'Aguilar), and a few days later at Cape Foulweather of Cook fame, close to the so-called straits discovered by the Greek pilot John da Fuca in 1592. Suddenly, relates Vancouver, "a sail was discovered to the westward. This was a very great novelty, not having seen any vessel during the last eight months. She soon hoisted American colours, and proved to be the ship Columbia, commanded by Captain Grey, belonging to Boston. He had penetrated about fifty miles into the disputed strait. He spoke of the mouth of a river that was inaccessible owing to breakers." (This was afterwards explored by Vancouver and named the Columbia River on which Washington now stands.)

Having examined two hundred and fifteen miles of coast, Vancouver and his two ships now entered the inlet—Da Fuca Straits—now the boundary between the United States and British Columbia. All day they made their way up the strait, till night came, and Vancouver relates with pride that "we had now advanced farther up this inlet than Mr. Grey or any other person from the civilised world."

"We are on the point of examining an entirely new region," he adds, "and in the most delightfully pleasant weather." Snowy ranges of hills, stately forest trees, vast spaces, and the tracks of deer reminded the explorers of "Old England." The crews were given holiday, and great joy prevailed. Natives soon brought them fish and venison for sale, and were keen to sell their children in exchange for knives, trinkets, and copper. As they advanced through the inlet, the fresh beauty of the country appealed to the English captain: "To describe the beauties of this region will be a very grateful task to the pen of a skilful panegyrist—the serenity of the climate, the pleasing landscapes, and the abundant fertility that unassisted nature puts forth, require only to be enriched by the industry of man with villages, mansions, and cottages to render it the most lovely country that can be imagined."

A fortnight was spent among the islands of this inlet, which "I have distinguished by the name of Admiralty Inlet," and on 4th June 1792 they drank the health of the King, George in a double allowance of grog, and on his fifty-fourth birthday took formal possession of the country, naming the wider part of the strait the Gulf of Georgia and the mainland New Georgia. The two ships then made their way through the narrow and intricate channels separating the island of Vancouver from the mainland of British Columbia, till at last, early in August, they emerged into an open channel discovered by an Englishman four years before and named Queen Charlotte's Sound. Numerous rocky islets made navigation very difficult, and one day in foggy weather the Discovery  suddenly grounded on a bed of sunken rocks. The Chatham  was near at hand, and at the signal of distress lowered her boats for assistance. For some hours, says Vancouver, "immediate and inevitable destruction presented itself." She grounded at four in the p.m. Till two next morning all hands were working at throwing ballast overboard to lighten her, till, "to our inexpressible joy," the return of the tide floated her once more. Having now satisfied himself that this was an island lying close to the mainland, Vancouver made for Nootka Sound, where he arrived at the end of August.

At the entrance of the Sound he was visited by a Spanish officer with a pilot to lead them to a safe anchorage in Friendly Cove, where the Spanish ship, under one Quadra, was riding at anchor. Civilities were interchanged "with much harmony and festivity. As many officers as could be spared from the vessel and myself dined with Senor Quadra, and were gratified with a repast we had lately been little accustomed to. A dinner of five courses, consisting of a superfluity of the best provisions, was served with great elegance; a royal salute was fired on drinking health to the sovereigns of England and Spain, and a salute of seventeen guns to the success of the service in which the Discovery  and Chatham  were engaged." But when the true nature of Vancouver's mission was disclosed, there was some little difficulty, for the Spaniards had fortified Nootka, built houses, laid out gardens, and evidently intended to stay. Vancouver sent Captain Broughton home to report the conduct of the Spaniards, and spent his time surveying the coast to the south. Finally all was arranged satisfactorily, and Vancouver sailed off to the Sandwich Islands. When he returned home in the autumn of 1794 he had completed the gigantic task of surveying nine thousand miles of unknown coast chiefly in open boats, with only the loss of two men in both crews—a feat that almost rivaled that of Captain Cook.

It has been said that Vancouver "may proudly take his place with Drake, Cook, Baffin, Parry, and other British navigators to whom England looks with pride and geographers with gratitude."