The most widely distributed member of the loon or diver family, it breeds primarily in Arctic regions, and winters in northern coastal waters.

First described by Danish naturalist Erik Pontoppidan in 1763, the red-throated loon is a monotypic species with no distinctive subspecies despite its large Holarctic range.

[6] The specific epithet stellata is Latin for "set with stars" or "starry",[7] and refers to the bird's speckled back in its non-breeding plumage.

[11] Like the other members of its genus, the red-throated loon is well adapted to its aquatic environment: its dense bones help it to submerge, its legs—in their set-back position—provide excellent propulsion, and its body is long and streamlined.

Its feet are large, its front three toes are fully webbed, and its tarsus is flattened, which reduces drag and allows the leg to move easily through the water.

In flight, when passing conspecifics or circling its own pond, it gives a series of rapid yet rhythmic goose-like cackles—kaa-kaa-kaa or kak-kak-kak, at roughly five calls per second.

Another call—a harsh, pulsed cooing that rises and falls in pitch, and is typically repeated up to 10 times in a row—is used in territorial encounters and pair-bonding, and by parent birds encouraging their young to move on land between bodies of water.

[23] At medium to close range, an adult red-throated loon in either breeding or non-breeding plumage is usually easily recognised.

However, in certain light conditions, at certain times in its moulting cycle, or at greater distances, it may be mistaken for another species—most commonly the black-throated loon, but also occasionally the great crested grebe.

[28] In Europe, it breeds in Iceland, northern Scotland, north-western Ireland (only a few pairs), Scandinavia and northern Russia, and winters along the coast as far south as parts of Spain; it also regularly occurs along major inland waterways, including the Mediterranean, Aegean and Black Seas, as well as large rivers, lakes and reservoirs.

[1] In Asia, it breeds in the northern stretches of Siberia, and winters along the Pacific coast as far south as China, Japan and Taiwan.

[22] Young use this method of covering ground when moving from their breeding pools to larger bodies of water, including rivers and the sea.

[22] In eastern North America (and possibly elsewhere), it tends to migrate near the coast rather than farther offshore;[33] Siberian populations travel for hundreds of miles over land en route to their southern European wintering grounds.

[35] Like all members of its family, the red-throated loon goes through a simultaneous wing moult, losing all its flight feathers at once and becoming flightless for a period of three to four weeks.

[36] Like all members of its family, the red-throated loon is primarily a fish-eater, though it sometimes feeds on molluscs, crustaceans, frogs, aquatic invertebrates, insects, fish spawn or even plant material.

[40] For the first few days after hatching, young red-throated loons are fed aquatic insects and small crustaceans by both parents.

[41] Young birds may be fed for some time after fledging; adults have been seen feeding fish to juveniles at sea and on inland lakes in the United Kingdom, hundreds of kilometres from any breeding areas.

[48] In Scotland, on the other hand, the population increased by some 16% between 1994 and 2006, according to surveys done by the Royal Society for the Protection of Birds and Scottish Natural Heritage.

[53] Studies in Sweden have also shown that they may be adversely impacted by the acidification of lakes, as the fish on which they prey are susceptible to low pH.

[59] The red-throated loon is susceptible to avian influenza[60] and Type E botulism,[61] and is regularly killed by the ingestion of neurotoxins produced by "red tide" algal blooms.

[62] During a 2007 bloom, large numbers of the birds also died of hypothermia, after their plumages became matted by a protein byproduct of the algae, which reduced the insulating properties of their feathers.

[63] Used as a food source since prehistoric times,[64][65] the red-throated loon is still hunted by indigenous peoples in some parts of the world today.

[67] In some parts of Russia, red-throated loon skins were traditionally used to make caps and various clothing decorations, including collars.

[69] According to the myth—which varies only slightly between versions, despite the sometimes-vast distances that separated the groups who believed it—the loon was asked by a great shaman to bring up earth from the bottom of the sea.

[70] As recently as the 1800s, the behaviour of the red-throated loon was used to forecast the weather; according to the conventional wisdom of the time, birds flying inland or giving short cries predicted good weather, while those flying out to sea or giving long, wailing cries predicted rain.

[48] The people of the Faroe Islands believed that if the red-throated loon miaowed like a cat, then rain was imminent, while a call of gaa-gaa-gaa or turkatrae-turkatrae predicted fine weather.

[71] Bhutan, Japan, Åland (an autonomous region of Finland), and the Union of the Comoros have issued stamps featuring the red-throated loon.