Mary McMullen, age 13, of Jamestown, N.Y., for her question:

WHO WAS THE FIRST TO SAIL THE NORTHWEST PASSAGE?

It wasn't until 1906 that a Norwegian explorer named Roald Amundsen became the first person to navigate the Northwest Passage all the way from the east to the west. Explorers had tried since 1500 to sail north of Canada from the Atlantic Ocean to the Pacific.

Aboard a ship named Gjoa, Amundsen proved that he was a careful planner and an expert surveyor. His observations also helped scientists to locate the North Pole.

But when Amundsen completed his Northwest Passage trip, he achieved a goal that many explorers had tried to reach for 400 years.

Soon after Columbus reached North America, explorers realized that the new land was not part of Asia, as they had believed at first. British, French and Dutch adventurers were eager to find a waterway that would take them around or through the continent.

The search for the Northwest Passage started in 1524 when Giovanni Verrazano, sailing under the French flag, tried to find the pass but only made it as far north as Maine.

Jacques Cartier, also sailing for France, found the St. Lawrence River in 1535.

Then in 1609, Henry Hudson, sailing for the Dutch East India Company, sailed into New York Bay and some distance up the Hudson River. He came back in 1610 and explored the Hudson Strait and Hudson Bay while searching for the Northwest Passage.

Over the years, many explorers tried to find the waterway that would connect one great ocean with another. Among the best were the sailors from England who included Sir Martin Frobisher, John Davis, William Baffin and Robert Bylot.

Then in 1848 a British explorer named Sir John Franklin died trying to find the passage to Asia. Many people honor Franklin as the first discoverer of the Northwest Passage, although he never completed the voyage through it. His ships reached a point not far from the waters that led directly to the Asiatic shore.

The first west to east voyage of the Northwest Passage wasn't completed until 1942. At that time, the Royal Canadian Mounted Police schooner, St. Roch, made the trip.

McClure Strait was finally conquered in 1954 by U.S. Navy and Coast Guard icebreakers. Three U.S. Coast Guard cutters, the Spar, the Bramble and the Storis, aided by the Canadian Navy icebreaker Labrador, made the first west to east trip in 1957. They traveled through the Bellot Strait. This narrow channel is big enough for freighters. It permits cargo ships to unload supplies for the Distant Early Warning radar line in northern Canada.

The Spar was the first ship ever to sail completely around North America on a continuous voyage. It started from Bristol, R.I., and went south to the Panama Canal, then up the Pacific Coast, through the Northwest Passage and back to Bristol.

In 1960, the U.S. atomic submarine Seadragon made the first underwater crossing of the Northwest Passage. Also in 1960, the U.S. icebreaker Manhattan became the first commercial ship to complete the passage.