After mapping it, and getting many turtle, he continued his course to the north, and discovered Atooi or Kauai, the western island of the Sandwich Group.
Communicating with this island and another, he finally left on February 3rd, 1778, and on March 7th made the coast of North America, a little south of the Columbia River.

Gales ensued, and Cook missed the entrance of Juan de Fuca Strait, making the land again a little north of it.
Anchoring first in Nootka Sound in Vancouver Island--though Cook did not know it was an island--the ships continued their exploration to the north-west, skirting the coast as near as stormy weather permitted them, and calling at various places until the north-west extremity of the Alaska Peninsula was reached.

In one place, afterwards called Cook's River, it was hoped that the desired passage eastward was found; but it was soon discovered that it was merely an inlet.
Passing through the Aleutian Chain, east of Unalaska, Cook visited that island, and continued his voyage through the Bering Sea, clinging to the land as much as possible, and finally got into Bering Strait.

Here he had both continents in sight, and communicated with both sides.
Standing further north, he, in latitude 70 degrees 30 minutes north, came across the icy barrier of the Arctic Sea.

After vainly trying for a passage in fog and strong wind, surrounded by loose ice, and after mapping a good deal of the shores on both sides, the ships again turned south at the end of August, exploring as they went first on the Asiatic side, and afterwards on the American, especially examining Norton Sound.
In the beginning of October they once more arrived at Unalaska, and the Resolution having sprung a dangerous leak, the opportunity was taken to stop it.
On October 26th the ships sailed for the Sandwich Islands, where Cook had determined to winter, for the double purpose of refreshing his crew, gaining more knowledge of the Group, and being in a convenient position for resuming his exploration in the spring.
The voyage just accomplished was very remarkable, whether for the amount of coast mapped, which extended for between three and four thousand miles, or for the determination with which it was prosecuted in tempestuous and thick weather, on a most dangerous and inhospitable coast, part of the time in ice.