Canada has the longest coastline of any country in the world at 243,042 kilometres when measured including all islands. This measurement was calculated by Statistics Canada using detailed satellite imagery and coastal mapping data. The coastline touches three oceans: the Pacific Ocean along British Columbia's western edge, the Atlantic Ocean on the eastern seaboard including the Maritime provinces and Newfoundland, and the Arctic Ocean across the entire northern perimeter from Yukon through the Northwest Territories and Nunavut to the northern tip of Labrador. No other nation borders three separate oceans.
The Bay of Fundy between New Brunswick and Nova Scotia records the highest tides in the world. The tidal range reaches 16.3 metres at Burntcoat Head in Nova Scotia's Minas Basin, measured during spring tides when lunar and solar gravitational forces align. The bay's funnel shape forces water into progressively narrower channels, amplifying tidal movement. At low tide, the seafloor extends kilometres from the shoreline, exposing mudflats and rock formations. The water returns within six hours. Twice daily this volume of water exceeds the combined flow of all freshwater rivers on Earth during that same period.
The St. Lawrence River connects the Great Lakes to the Atlantic Ocean and forms part of the Canada-United States border from Lake Ontario to Trois-Rivières, Quebec, where it flows entirely within Canadian territory. The river is 1,197 kilometres long from the outflow of Lake Ontario at Kingston to the Gulf of St. Lawrence. Jacques Cartier reached the river in 1535 and claimed the surrounding territory for France. Samuel de Champlain founded Quebec City on the river's north shore in 1608. The St. Lawrence Seaway, completed in 1959, is a system of locks, canals, and channels that allows ocean-going vessels to travel from the Atlantic to Lake Superior. Ships pass through seven locks on the Canadian side between Montreal and Lake Ontario, raising vessels 75 metres above sea level.
The Great Lakes form the largest group of freshwater lakes on Earth by total surface area at 244,106 square kilometres. Lake Superior, Lake Huron, Lake Michigan, Lake Erie, and Lake Ontario contain 21 percent of the world's surface freshwater by volume. Canada shares four of these lakes with the United States, with Lake Michigan lying entirely within U.S. territory. Lake Superior is the largest freshwater lake by surface area in the world at 82,100 square kilometres. The Welland Canal bypasses Niagara Falls, connecting Lake Ontario to Lake Erie through eight locks that lift ships 99.5 metres. The canal opened in 1829 and has been rebuilt multiple times, with the current fourth iteration completed in 1932.
Hudson Bay is a large inland sea in northeastern Canada covering 1,230,000 square kilometres. The bay is connected to the Atlantic Ocean through Hudson Strait to the north and to the Arctic Ocean through Foxe Channel. Henry Hudson explored the bay in 1610 while searching for the Northwest Passage, and the bay carries his name despite his crew mutinying and setting him adrift the following year. The Hudson's Bay Company received a royal charter from King Charles II in 1670 granting trading rights to the entire watershed draining into Hudson Bay, an area called Rupert's Land that covered 3.9 million square kilometres. The company controlled this territory for 200 years until transferring it to the Canadian government in 1870.
The Mackenzie River is Canada's longest river system at 4,241 kilometres when measured from the headwaters of the Finlay River in British Columbia to the Beaufort Sea in the Arctic Ocean. The river was named after Alexander Mackenzie, who traveled its length to the Arctic Ocean in 1789. The Mackenzie proper begins at Great Slave Lake in the Northwest Territories and flows 1,738 kilometres north to the Beaufort Sea. The river's delta covers 13,135 square kilometres, the second-largest river delta in the Arctic after the Lena Delta in Russia. The Mackenzie carries an average discharge of 9,700 cubic metres per second, making it the largest river flowing into the Arctic Ocean from North America.
The Inside Passage is a coastal waterway running from Puget Sound in Washington State through British Columbia to Southeast Alaska. The Canadian portion extends roughly 900 kilometres from the Canada-U.S. border near Vancouver Island to the Alaska border. The passage consists of channels between the mainland coast and a series of offshore islands including Vancouver Island, the largest island on the Pacific coast of North America at 32,134 square kilometres. BC Ferries operates the Inside Passage route between Port Hardy on Vancouver Island and Prince Rupert on the mainland coast, a journey of 491 kilometres taking 15 hours. The passage provides shelter from Pacific Ocean swells and has been used as a transportation corridor for thousands of years by Indigenous peoples including the Haida, Tsimshian, and Kwakwaka'wakw.
The Fraser River is British Columbia's longest river at 1,375 kilometres, flowing from the Rocky Mountains near the Alberta border to the Strait of Georgia at Vancouver. Simon Fraser of the North West Company traveled the river in 1808, believing he had found the Columbia River. The Fraser is the largest salmon-producing river system in the world, supporting all five species of Pacific salmon. The river's discharge varies dramatically between winter low flows around 1,000 cubic metres per second and peak freshet flows that can exceed 15,000 cubic metres per second in late spring when mountain snowpack melts. The 1894 freshet reached an estimated 17,000 cubic metres per second. Hell's Gate in the Fraser Canyon is the river's narrowest point, where the entire volume passes through a gorge 33.5 metres wide.
The Northwest Passage is a sea route connecting the Atlantic and Pacific oceans through the Canadian Arctic Archipelago. European explorers sought this route for centuries, with John Cabot searching in 1497 and Martin Frobisher making three attempts in the 1570s. Roald Amundsen completed the first successful transit from 1903 to 1906 in the sloop Gjøa, taking three years and wintering in the Arctic twice. The passage consists of several possible routes through channels between Arctic islands. Canada claims the waters of the Northwest Passage as internal waters under Canadian sovereignty, while the United States and European Union classify them as international straits. The Manhattan, a specially reinforced oil tanker, transited the passage in 1969 without requesting Canadian permission, prompting Canada to pass the Arctic Waters Pollution Prevention Act in 1970.
The Canadian Arctic Archipelago consists of 36,563 islands covering 1,400,000 square kilometres in the Arctic Ocean north of mainland Canada. Baffin Island is the largest at 507,451 square kilometres, making it the fifth-largest island in the world after Greenland, New Guinea, Borneo, and Madagascar. Victoria Island is the eighth-largest island in the world at 217,291 square kilometres. Ellesmere Island extends to Cape Columbia at 83°06'N, the northernmost point of land in Canada and 769 kilometres from the geographic North Pole. The archipelago was largely unmapped until the 20th century, with the last major island, Mackenzie King Island, discovered in 1915.
The Atlantic coast of Canada extends from the Canada-United States border in the Bay of Fundy through the Maritime provinces and around Newfoundland and Labrador to Hudson Strait. The coastline is characterized by rocky shores, deep harbors, and extensive fishing grounds. The Grand Banks off Newfoundland is a continental shelf area covering 282,500 square kilometres where the cold Labrador Current meets the warm Gulf Stream, creating conditions that historically supported massive cod populations. Portuguese and Basque fishermen reached the Grand Banks by the early 1500s, with John Cabot reporting cod so plentiful in 1497 that they could be caught in baskets weighted with stones. The northern cod stock collapsed in 1992 after decades of overfishing, and Canada imposed a moratorium that remains in effect.
The Rideau Canal connects Ottawa on the Ottawa River to Kingston on Lake Ontario, a distance of 202 kilometres through a series of rivers, lakes, and constructed channels. Lieutenant Colonel John By of the Royal Engineers supervised construction from 1826 to 1832, completing the canal in five years at a cost of £822,804. The canal was built following the War of 1812 to provide a secure supply route between Montreal and Lake Ontario that could not be attacked from the United States border. The system uses 47 locks to manage an elevation change of 83 metres between Ottawa and Kingston. The canal became a UNESCO World Heritage Site in 2007 as the best-preserved example of a slack-water canal in North America and the only canal from the great North American canal-building era still operating along its original route with original structures.
The Ottawa River forms much of the border between Ontario and Quebec, flowing 1,271 kilometres from its source at Lake Capimimichigama in Quebec to its confluence with the St. Lawrence River at Montreal. Samuel de Champlain traveled the river in 1613 and 1615 while exploring routes to the interior. The river became the primary route for the fur trade, with voyageurs using it to reach the Great Lakes and beyond. The timber trade transformed the Ottawa Valley in the 19th century, with square timber rafts floating downstream to Quebec City for export to Britain. The Chaudière Falls at Ottawa had a natural drop of 15 metres before industrial development and dam construction altered the falls. Hydroelectric development on the Ottawa River generates 2,000 megawatts of electricity from facilities operated by Ontario Power Generation and Hydro-Québec.
Lake Superior is the deepest of the Great Lakes with a maximum depth of 406 metres. The lake has a surface area of 82,100 square kilometres and contains 12,100 cubic kilometres of water, enough to cover North and South America to a depth of 30 centimetres. The lake's retention time is 191 years, meaning water entering the lake remains for nearly two centuries before flowing out through the St. Marys River. The lake's cold water inhibits decomposition, preserving shipwrecks in near-pristine condition. The Edmund Fitzgerald sank in Lake Superior on November 10, 1975, during a severe storm, killing all 29 crew members. The wreck lies in two pieces at a depth of 160 metres. Lake Superior State University in Sault Ste. Marie, Michigan, maintains a registry of Great Lakes shipwrecks documenting more than 350 wrecks in Lake Superior alone.
The Saguenay Fjord in Quebec is the southernmost fjord in the Northern Hemisphere, extending 105 kilometres from the St. Lawrence River to Chicoutimi. The fjord reaches depths of 275 metres, deeper than the adjacent St. Lawrence. Glacial action during the last ice age carved the fjord through the Canadian Shield, with ice up to two kilometres thick scouring the valley. The dark waters of the Saguenay River, stained by organic matter from the boreal forest, meet the saltwater of the St. Lawrence at the fjord mouth, creating a mixing zone that draws beluga whales, minke whales, and fin whales. Parks Canada protects the fjord and surrounding marine environment in Saguenay–St. Lawrence Marine Park, established in 1998 as Canada's first marine park. The park covers 1,245 square kilometres of marine habitat.
The Columbia River rises in Columbia Lake in the Rocky Mountain Trench of British Columbia and flows 2,000 kilometres to the Pacific Ocean, with only the first 801 kilometres in Canada. David Thompson of the North West Company mapped the entire length of the river from 1807 to 1811, establishing fur trading posts along its course. The Treaty of Washington in 1846 established the Canada-United States border at the 49th parallel, dividing the Columbia Basin between the two countries. The Columbia River Treaty signed in 1961 and ratified in 1964 coordinated water management between Canada and the United States, with Canada agreeing to build three dams in British Columbia and the U.S. paying Canada for flood control benefits and half the value of increased hydroelectric generation downstream. The treaty operates in perpetuity but contains provisions allowing either country to terminate portions with ten years' notice starting in 2024.
The Labrador Sea lies between Labrador and Greenland, connecting the Atlantic Ocean to Baffin Bay through Davis Strait. The Labrador Current flows south along the Labrador coast carrying cold Arctic water and icebergs from Greenland glaciers. The current moves at speeds up to 40 kilometres per day and meets the warm Gulf Stream off Newfoundland, creating the foggy conditions characteristic of the Grand Banks. An estimated 40,000 icebergs calve from Greenland glaciers each year, with about 400 to 800 reaching the shipping lanes off Newfoundland. The International Ice Patrol was established in 1914 following the sinking of the Titanic in 1912, which struck an iceberg at 41°46'N 50°14'W approximately 600 kilometres south of Newfoundland.
The Strait of Georgia separates Vancouver Island from mainland British Columbia, extending 240 kilometres from north to south with widths ranging from 20 to 60 kilometres. Captain George Vancouver surveyed the strait in 1792 and named it the Gulf of Georgia after King George III, though it is more accurately classified as a strait. The Fraser River enters the strait at its southern end, creating a brackish mixing zone. The BC Ferries system operates multiple routes across the strait, with the Tsawwassen to Swartz Bay route carrying approximately four million passengers annually on a 36-kilometre crossing taking 95 minutes. The strait supports significant marine traffic including container ships, cruise ships, and fishing vessels. The waters contain substantial populations of orcas, with the Southern Resident killer whale population numbering 75 individuals as of 2023 census counts.
The Saint John River in New Brunswick flows 673 kilometres from its source in Maine to the Bay of Fundy at Saint John. The river is notable for the Reversing Falls Rapids where the river meets the bay. At low tide, the river flows normally over a series of rapids and falls into the bay. At high tide, the enormous tidal range in the Bay of Fundy forces water back up the river, reversing the falls and creating upstream rapids. At slack tide between the two flows, the water surface appears calm for approximately 20 minutes. Samuel de Champlain reached the river mouth on the feast day of John the Baptist in 1604 and named it accordingly. The river valley supported Acadian settlements until the Expulsion of 1755, when British authorities forcibly removed French-speaking inhabitants.
The Churchill River in Labrador flows 856 kilometres from the Labrador Plateau to Lake Melville and Hamilton Inlet on the Atlantic coast. The river drops 316 metres over Churchill Falls, which had an average flow of 2,100 cubic metres per second before hydroelectric development. The Churchill Falls Generating Station built from 1967 to 1974 is one of the largest underground power stations in the world, with an installed capacity of 5,428 megawatts from 11 turbines. The project involved diverting the river through 88 kilometres of tunnels and flooding 6,988 square kilometres to create the Smallwood Reservoir. Newfoundland and Labrador owns the generating station through Nalcor Energy, but a 1969 contract requires selling the vast majority of power to Hydro-Québec at fixed rates that now appear dramatically below market value. This contract remains in effect until 2041.
The Yukon River begins at Tagish Lake in British Columbia, flows through Yukon territory, and enters Alaska where it continues 3,190 kilometres to the Bering Sea. Only 1,149 kilometres flow through Canada. The river gave its name to Yukon Territory when it was separated from the Northwest Territories in 1898 during the Klondike Gold Rush. Prospectors traveling to Dawson City would take ships from Seattle or Vancouver to Skagway, Alaska, cross the Chilkoot Pass or White Pass to reach the headwaters of the Yukon River system, build boats or rafts, and float 800 kilometres downriver to Dawson. An estimated 100,000 people attempted the journey during 1897-1898, with roughly 30,000 reaching the goldfields. The White Pass & Yukon Route railway completed in 1900 provided a less arduous route but arrived after the peak of the rush.
The Skeena River in British Columbia flows 610 kilometres from the Spatsizi Plateau to Chatham Sound near Prince Rupert. The river is the second-longest undammed river system in British Columbia after the Fraser, allowing salmon to spawn throughout its length. The river supports populations of all five Pacific salmon species plus steelhead trout. The Grand Trunk Pacific Railway completed a line along the Skeena River valley in 1914, connecting Prince Rupert to the national rail network. The route required extensive engineering including tunnels and bridges through the coastal mountains. Highway 16 follows much of the same route along the river valley, completed as a gravel road in 1944 and paved in sections through the 1970s and 1980s.