What did James Cook set out to discover?

James Cook made 3 major voyages of discovery, and his goals differed with each voyage.

First Voyage (1768 - 1771)

Cook was hired by the British Royal Geographical Society to observe the transit of Venus across the sun from the vantage point of Tahiti in the Pacific Ocean. After this, whilst still on this mission, Cook had orders to head south and west and secretly search for the unknown Great Southern Continent, or Terra Australis Incognita before other countries, especially France, reached it first. His mission and goal was to make extensive notes on the flora and fauna of the land, and determine whether or not it would be suitable for colonisation. If so, he was to claim it in the name of Britain.

He did not find this mysterious continent, but did go onto to map New Zealand and the East Coast of Australia, and claim these for Britain.

Second Voyage (1772 - 1775)

Although Cook was convinced that the the Great Southern Continent did not exist, there were many in the scientific community who still insisted that this mysterious rich continent was still to be found in the south hemisphere somewhere.

Cook proposed a second voyage whose goal was to prove or disprove the theory once and for all. The Royal Navy approved his plan. He delved deep into the southern Indian ocean, being the first to cross the Antarctic Circle; he criss-crossed the South Pacific a number of times at different latitudes; he then explored the unknown areas of the South Atlantic.

By the time he was finished, although he had added many islands to the maps, there was now no doubt that Terra Australis Incognita simply did not exist. This result was finally accepted back in Britain. In this case he had not set out to "discover" something - but to disprove a myth.

Third Voyage (1776 - 1779)

In order for ships from Europe to reach the rich markets of Asia, they had to sail vast distances - either under Africa and then across to Asia, or under South America. There was a theory that there might be a much faster way. If only the European ships could travel across the top of Canada going almost directly from the Atlantic and into the Pacific ocean. This fabled route was known as the North-West Passage.

A prize of £20,000 had been offered in Britian for anyone who could find this passage. After being hailed as a naval hero for his second voyage, the authorities offered James Cook, now in semi-retirement, a chance to find it - and he accepted.

After entering the Pacific, Cook's ships sailed north and discovered the islands of Hawaii. They then sailed along the North-West coast of America, filling in the maps as they went. Sailing through the Bering Strait between Russia and Alaska they then started their attempt to find the Passage in Arctic waters. They failed and almost came to disaster a number of times.

With the ships in poor repair, they travelled south to the newly discovered Hawaiian Islands. After initially being well received by the Islanders, an altercation led to Cook being killed by the Hawaiian natives. Despite his loss, his expedition made a second attempt to find the North-West Passage, and similarly failed.

In modern times with the right sort of Ice-Breaker ship, it is possible to make the journey. From the point of view of Cook's time, with wooden sailing ships, the North-West Passage simply did not exist.