Icebreakers are best defined by their primary uses: to break sea ice, to manœuvre in heavy concentrations of pack ice, and to clear channels through which other ships can pass in safety. Ice-strengthened ships, in contrast, are normally cargo transport ships strengthened for use in ice. Heavily reinforced hulls, a sloping forefoot and a ratio of horse-power to displacement of more than unity are characteristics common to both types; the icebreaker being usually distinguished by more powerful engines, higher ratio of beam to length, smaller cargo capacity and such distinctive features as heeling tanks. Icebreakers designed for use in regions other than the Arctic or Antarctic, e.g. in the Baltic or Gulf of St Lawrence, may possess one or two forward propellers, which are not found in polar icebreakers.

The understanding of ice, especially of sea ice, is basic to Canada's defence and economic development and yet, up to 1956, little had been done in Canada to study the formation, development and degeneration of sea ice. The National Research Council had been engaged in ice studies, but the emphasis here had been on fresh-water ice. Glaciological studies had been carried out by several universities, by the Geophysics Section of the Defence Research Board, and by other government departments.

Russian scientists have long been interested in the tundra. M. B. Lomonosov, in 1763, referred to “the places overgrown with mosses, which cover most parts of the Northern Ocean shores, excluding bogs and forests” as tundras. This early definition emphasized, therefore, the proximity of the tundra zone to the Arctic Ocean coast, the predominance of mosses in its vegetational cover (Lomonosov probably included lichens as “mosses”), and the absence of trees. The treelessness of the tundra, its outstanding characteristic, is a fundamental feature in its geography.

When research under the IGY programme began in Antarctica, the Soviet Union undertook the task of studying vast areas of the sector south of the Indian Ocean.

In 1956, the First Combined Antarctic Expedition headed by M. M. Somov set up the main base, Mirny observatory, on the Davis Sea coast. This was followed by five subsequent expeditions inland during which new stations have been established hi the heart of Antarctica.

Polish expeditions to Vestspitsbergen between 1956 and 1960 were organized in connexion with the Third IGY and its continuation. The main area chosen for scientific investigations was Hornsund, Vestspitsbergen, in which, at Isbjørnhamna, the main station was built (lat. 77° N., long. 15° 30′ E.). The areas covered by investigations were mainly southern and central parts of Wedel Jarlsberg Land and Torell Land, to the north of Hornsund, and the northern part of Sørkapp Land, to the south of Hornsund. Brief investigations were also carried out to the south of Van Keulenfjorden, in north-west Torell Land, and along the western, southern and eastern coasts of Sørkapp Land.

In February 1902, members of Scott's Discovery expedition found the remains of a fish 18 in. long on the surface of the “pinnacled ice” near the ice front of the Ross Ice Shelf in McMurdo Sound. In 1903, a party under Wilson found three Nototheniid fishes, sponges, shells, and seaweeds among similar ice on the floating section of the Koettlitz Glacier. The fishes, which were up to 48 in. in length, were all headless. They resembled a specimen caught in a seal blow-hole near the Discovery winter quarters, whose head was bitten off by a seal before it could be landed, but whose body weighed 40 Ib. and was 46 in. long. This fish was a Notothenia, close to N. colbecki Boulenger. In 1911, a party under Taylor found another large headless fish, which may have been as much as 4 ft. long, embedded in the ice of the Lower Koettlitz Glacier some 5 miles from its seaward end, and among the pinnacled ice near the Dailey Islands the same party found corals, shells, sponges, patches of sediment, and about a dozen small fish. The ice in this region was so rich in sponges that it was difficult to get spicule-free ice for cooking.