The Great Northern Loon (Gavia immer), is a large member of the loon, or diver, family of birds. The species is known as the Common Loon in North America and the Great Northern Diver in Eurasia; its current name is a compromise proposed by the International Ornithological Committee. The European name "diver" comes from the bird's habit of catching fish by swimming calmly along the surface and then abruptly plunging into the water. The North American name "loon" is a reference to the bird's clumsiness on land, and is derived from Scandinavian words for lame, such as Icelandic "lúinn" and Swedish "lam".

This species, like all divers, is a specialist fish-eater, catching its prey underwater, diving as deep as 200 feet (60 m). Freshwater diets consist of pike, perch, sunfish, trout, and bass.

This loon is well known in Canada, appearing on the $1 ("loonie") coin and the previous series of $20 bill, and is the provincial bird of Ontario.

One of my favorite sounds in the early morning, or early evening is that of a Loon. It is something you just can't forget.