Which countries were the most active in Arctic exploration?

1. RUSSIA: In addition to having the largest Arctic area of any country, Russia also claimed what is now Alaska - and sold it to the USA in 1867.

2. GREAT BRITAIN: The highest level of North American Arctic exploration of any country, claiming vast portions of what is now Nunavut. These territories were given to Canada in the 19th century.

3. NORWAY: One of the most active, today Norway holds the Svalbard Islands. Roald Amundsen navigated the Northwest Passage, Fridtjof Nansen explored Greenland, and Otto Sverdrup discovered islands in the Canadian Arctic - which he claimed for Norway and then sold back to Canada.

4. DENMARK: Claimed both Greenland (still a Danish territory) and Iceland (independent since 1944). Denmark is now claiming that a ridge attached to Greenland should give it sovereignty over the North Pole.

5. SWEDEN: Swedish explorer Nils Nordenskjold was the first to complete a voyage through the Northeast Passage.

6. UNITED STATES OF AMERICA: Americans Robert Peary and Matthew Henson (aided by four Inuit) planted the American flag on the North Pole, and Richard E. Byrd was the first to fly over the Pole.