The Red-throated Diver, known in North America as Red-throated Loon (Gavia stellata) is the smallest and most widely distributed member of the loon or diver family.

The Red-throated Diver is typically 55-67 cm (24" to 27") in length with a 91-110 cm wingspan. Breeding adults have a grey head, thick neck, red throat, white underparts and dark mantle. Non-breeding plumage is drabber with the chin, foreneck and much of the face white. Its thin upturned bill is grey in summer and whitish in winter, though the change may occur at a different time to the change in plumage. As an adaptation for diving its nostrils are narrow and elongated. Its iris is red. It weighs between one and 1.2 kg. The call is an a yodelling high-pitched wailing.

Breeding in northern Eurasia and Arctic Canada, the Red throated Diver winters over a much wider range on coasts and on large lakes. It breeds mostly on fresh water but still feeds largely in the sea even when breeding, thus allowing it to breed on small lakes than Black-throated Diver, which feeds on freshwater lakes, but is more tied to coastal environments.

This species, like all divers, is a specialist fish-eater, diving over 7.5 m (25 feet) to catch its prey. Although loons are very clumsy on land, the red-throated diver is able to walk longer distances. It is even able to take off directly from land, the only species of diver that can. It flies with neck outstretched. After breeding time it moves to coastal waters. The Red-throated Diver spends long hours caring for its plumage. Its complex bathing practices involves diving, rolling and wing shaking. It has also a very ritualized mating behavior. It is monogamous, forming long-term pair bonds. Copulation takes place on land and is repeated frequently.

Other regional names include Cape drake, cape race, cobble, little loon, pegging-owl loon, pepper-shinned loon, rain-goose, scape-grace, sprat loon.

The Red-throated Diver is one of the species to which the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA) applies.

On September 6, 2007, RSPB Scotland and the Scottish Natural Heritage (SNH) stated that it was surprised by an increase in the last 12 years in the breeding figures in the UK for the Red-throated Diver and the rarer Black-throated Diver of 16% and 34% respectively due to the anchoring of 58 man-made rafts in lochs.

Both species decreased in Europe but in Scotland, Red-throated Diver numbers rose from 187 pairs in 1994 to 217 pairs in 2006. The greatest increase was in the Western Isles and also improved in the Highlands. Stuart Benn of the RSPB, said that rafts caused the increase, since the numbers rose from 935 to 1,255 breeding pairs in 12 years. In Shetland numbers dropped from 700 pairs to 407. In mythology, the Red-throated Diver is known as the rain goose in Orkney and Shetland, and as a foreteller of storms. Dr Mark Eaton, RSPB scientist traced the drop in overall numbers to warming of the North Sea which reduced stocks of the fish on which they feed.