Canada has had an icebreaker capability for over 100 years. Indeed, one of the promises of Confederation - a guaranteed year-round ferry service between Prince Edward Island and the mainland - resulted between 1876 and 1899 in the construction of 3 small icebreaking FERRIES. At the turn of the century Canada's first full icebreakers, the Champlain and Montcalm, were built to break up ice barriers and dams that caused annual flooding at narrow points along the ST LAWRENCE RIVER.

Icebreakers were first used in the Canadian Arctic in the 1920s to deliver supplies and services to Native and isolated settlements during the short summer season, and to back up claims of Canadian sovereignty over the NORTHWEST PASSAGE and ARCTIC ARCHIPELAGO. In the 1930s the port of Churchill was opened for grain shipments, and in 1957 the government undertook the annual supply of Distant Early Warning (DEW) line sites across the Arctic.

Canada operates 21 of the world's estimated 110 icebreakers: 19 owned by the CANADIAN COAST GUARD (CCG) as part of Transport Canada and 2 by private firms. An icebreaker's chief function is to break, separate or divert ice in ice-covered waters, and the CCG icebreaker fleet has been designed and built for specified Canadian needs: to assist shipping in lakes, oceans and river mouths; to keep channels open through the ST LAWRENCE SEAWAY system; and to support government supply and economic development operations in the Arctic. The CCG icebreakers are classified as heavy (2 vessels), medium (6 vessels), and light (11 vessels). Canada's most powerful icebreaker, the Louis S. St. Laurent of 13 500 tons displacement (dwt), is smaller than Russia's four 13 300 dwt nuclear-powered icebreakers of the Rossiya class in service. The Canmar Kigoriak (7200 dwt) owned by Canadian Marine Drilling Ltd, though now mainly inactive, was used to convoy other kinds of marine units working in Arctic ice, such as drilling rigs; it was basically experimental, the prototype for the gigantic 200 000 dwt icebreaker-tanker of the future.

Canada, like all nations with icebreakers (Argentina, Finland, Sweden, Japan, W Germany, the US and Russia), operates many other kinds of ships built to function in ice conditions. These ice-strengthened marine units range from experimental cargo ships, such as the M.V. Arctic, to the mobile arctic caissons owned by large private companies involved in offshore oil drilling in the Beaufort Sea.

Heavy icebreakers in the CCG fleet generally operate in southern waters in the winter months and the Arctic during the summer. Though the Louis S. St. Laurent has worked in Hudson Bay in Dec, no serving Canadian icebreaker is able to penetrate Canadian Arctic water during the severe winter season from November to May.

The present Arctic numbers classification is part of the Canadian Arctic Shipping Pollution Prevention Regulations instituted in 1970. For example, an Arctic 4 icebreaker, which is the category assigned the Canmar Kigoriak, can maintain in general terms a speed of 3 knots through ice 0.91 metres (3 feet) thick in what is called "the continuous mode." This expression refers to the steady movement forward of the icebreaker through the water. An Arctic 7 icebreaker can maintain a speed of 3 knots through ice 7 feet thick. There are 4 Canadian Arctic Classifications (CAC) for icebreakers and all other ships strengthened for ice. A CAC 1 ship is designed for continuous operation in multi-year ice, while a CAC 4 vessel operates mostly in first-year ice. The knowledge of the icebreaker's crew is a key component of operating in ice.

In July and August 1994, the icebreakers CCG Louis S. St. Laurent and the US Coast Guard Polar Sea carried out the first Canada/USA Joint Scientific Expedition to the Arctic Basin and the NORTH POLE. It involved 60 Canadian and US scientists in about 30 research activities focused on understanding the Arctic region in the era of global change. These included, for example, ocean properties of circulation and ice cover as well as atmospheric radiation and the Greenhouse Effect. Though not originally scheduled as part of the expedition, on August 22, both ships reached the North Pole as the first North American surface ships to do so over the long, unexplored sea route from the western end of the Arctic Ocean.

Canada's future need for advanced icebreakers is not likely to be as large as that of Russia. The composition of Canada's icebreaker fleet depends on the level of demand for their services in ice-covered waters. For example, the transportation of oil and gas from the Arctic by water would result in a considerable increase in the icebreaking capability in Canada.