In the summer of 1778, Captain James Cook, the famous British explorer, tried to find a Western entrance to the Northwest Passage. This passage, he hoped, would be a 32______________between the Far East and the West. It could open up trade between continents.

Boating life was a bit different then, though. Cook’s boat was covered in ice, and his shipmates constantly tried to avoid slipping and falling. They 33_______________about having to eat walrus meat.

The British expedition was halted north of the Bering Strait. The ship hit “ice which seemed to be 10 or 12 feet 34_______________at least,” according to the captain’s journal. Cook’s ships followed the ice 35_______________all the way to Siberia, in Russia. Their search for the Northwest Passage came up empty.

More than two centuries later, scientists are studying records kept by Cook and his 36_______________. They are finding details about global warming. It has changed the Arctic in a way Cook could never have imagined.

Many people believed that oceans couldn’t freeze. Cook proved them wrong. Many people thought that sea ice 37______________in rivers. He proved that wrong, too.

Cook also described different types of sea ice. He saw the thick ice walls and ridges in the Arctic. He guessed that it 38_______________years for the ice to build up.