Icebreaker in the context of "Royal Danish Navy"

The Great Lakes Waterway (GLW) is a system of natural channels and artificial locks and canals that enable navigation between the North American Great Lakes. Although all of the lakes are naturally connected as a chain, water travel between the lakes was impeded for centuries by obstacles such as Niagara Falls and the rapids of the St. Marys River.

Its principal civil engineering works are the Welland Canal between Lakes Ontario and Erie, and the Soo Locks between Huron and Superior. Dredged channels were constructed in the St. Marys River, the Detroit River, Lake St. Clair and the St. Clair River between Huron and Erie. Usually, one or more U.S. Coast Guard icebreakers help keep the water passage open for part of the fall and early winter, although shipping usually ceases for two to three months thereafter. The St. Lawrence Seaway allows navigable shipping from the GLW to the Atlantic Ocean, while the Illinois Waterway extends commercial shipping to the Mississippi River and the Gulf of Mexico. The Great Lakes Waterway is co-administered by the governments of Canada and the United States.

Drift ice, also called brash ice, is sea ice that is not attached to the shoreline or any other fixed object (shoals, grounded icebergs, etc.). Unlike fast ice, which is "fastened" to a fixed object, drift ice is carried along by winds and sea currents, hence its name. When drift ice is driven together into a large single mass (>70% coverage), it is called pack ice. Wind and currents can pile up that ice to form ridges up to dozens of metres in thickness. These represent a challenge for icebreakers and offshore structures operating in cold oceans and seas.

Drift ice consists of ice floes, individual pieces of sea ice 20 metres (66 ft) or more across. Floes are classified according to size: small – 20 metres (66 ft) to 100 metres (330 ft); medium – 100 metres (330 ft) to 500 metres (1,600 ft); big – 500 metres (1,600 ft) to 2,000 metres (6,600 ft); vast – 2 kilometres (1.2 mi) to 10 kilometres (6.2 mi); and giant – more than 10 kilometres (6.2 mi).

The Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC, /ˌməʊˈzɛɪɪk/) expedition was a one-year-long expedition into the Central Arctic (September 2019 - October 2020). For the first time a modern research icebreaker was able to operate in the direct vicinity of the North Pole year round, including the nearly half year long polar night during winter. In terms of the logistical challenges involved, the total number of participants, the number of participating countries, and the available budget, MOSAiC represents the largest Arctic expedition in history.

During its one-year-long journey, the central expedition ship, the research icebreaker Polarstern from Germany's Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI), was supported and resupplied by the icebreakers and research vessels Akademik Fedorov and Kapitan Dranitsyn (Russia), Sonne and Maria S. Merian (Germany) and Akademik Tryoshnikov (Russia). In addition, extensive operations involving helicopters and other aircraft were planned. In total, during the various phases of the expedition, more than 600 people were working in the Central Arctic. The international expedition, which involved more than 80 institutions from 20 countries (Austria, Belgium, Canada, China, Denmark, Finland, France, Germany, Italy, Japan, the Netherlands, Norway, Poland, Russia, South Korea, Spain, Sweden, Switzerland, the United Kingdom, and the United States), was conducted by the AWI and was led by the polar and climate researcher Markus Rex and co-led by the atmospheric researcher Matthew Shupe from the University of Colorado Boulder. MOSAiC's main goals were to investigate the complex and still only poorly understood climate processes at work in the Central Arctic, to improve the representation of these processes in global climate models, and to contribute to more reliable climate projections.

USS Glacier (AGB-4) (later USCGC Glacier (WAG/WAGB-4)) was a U.S. Navy, then U.S. Coast Guard icebreaker which served in the first through fifteenth Operation Deep Freeze expeditions. Glacier was the first icebreaker to make her way through the frozen Bellingshausen Sea, and most of the topography in the area is named for her crew members. When built, Glacier had the largest capacity single armature DC motors ever installed on a ship. Glacier was capable of breaking ice up to 20 feet (6.1 m) thick, and of continuous breaking of 4-foot (1.2 m) thick ice at 3 knots (5.6 km/h; 3.5 mph).

Named for Glacier Bay, Alaska, USS Glacier was launched on 27 August 1954 at Ingalls Shipbuilding Corp., Pascagoula, Mississippi, sponsored by Mrs. Roscoe F. Good; and commissioned on 27 May 1955, CDR. E.H. Mayer USN, Commanding. Glacier is the only icebreaker built in the Glacier class, and was in U.S. Navy service for 11 years, and U.S. Coast Guard service for 21 years.

Nuclear marine propulsion is propulsion of a ship or submarine with heat provided by a nuclear reactor. The power plant heats water to produce steam for a turbine used to turn the ship's propeller through a gearbox or through an electric generator and motor. Nuclear propulsion is used primarily within naval warships such as nuclear submarines and supercarriers. A small number of experimental civil nuclear ships have been built.

Compared to oil- or coal-fuelled ships, nuclear propulsion offers the advantage of very long intervals of operation before refueling. All the fuel is contained within the nuclear reactor, so no cargo or supplies space is taken up by fuel, nor is space taken up by exhaust stacks or combustion air intakes. The low fuel cost is offset by high operating costs and investment in infrastructure, however, so nearly all nuclear-powered vessels are military.

A nuclear-powered icebreaker is an icebreaker with an onboard nuclear power plant that produces power for the vessel's propulsion system. Although more expensive to operate, nuclear-powered icebreakers provide a number of advantages over their diesel-powered counterparts, especially along the Northern Sea Route where diesel-powered icebreaker operations are challenging due to the heavy power demand associated with icebreaking, limited refueling infrastructure along the Siberian coast, and the endurance required. As of 2025, Russia is the only country that builds and operates nuclear-powered icebreakers, having built a number of such vessels to aid shipping along the Northern Sea Route and Russian arctic outposts since the Soviet era.

Aurora Borealis is a proposed European research icebreaker, comparable to the world's strongest icebreakers, planned jointly by a consortium of fifteen participant organizations and companies from ten European nations. If built, she would be the largest icebreaker ever built as well as the first icebreaker built to the highest IACS ice class, Polar Class 1.

The unique feature of the proposed vessel is its ability to perform scientific deep sea drilling in a sea ice covered ocean. The ship is proposed to have an operational lifetime of 35 to 40 years, with the main area of operations being the inner Arctic Ocean.

A tugboat or tug is a marine vessel that manoeuvres other vessels by pushing or pulling them, with direct contact or a tow line. These boats typically tug ships in circumstances where they cannot or should not move under their own power, such as in crowded harbors or narrow canals, or cannot move at all, such as barges, disabled ships, log rafts, or oil platforms. Some are ocean-going, and some are icebreakers or salvage tugs. Early models were powered by steam engines, which were later superseded by diesel engines. Many have deluge gun water jets, which help in firefighting, especially in harbours.