Dolly Varden are char of coastal streams of the northern Pacific Ocean. In the eastern Pacific they range from the Bering Sea to Washington State. In the northwest they range from Siberia to Japan and the Korean Peninsula. They inhabit coastal streams and lakes, although in Canada they are found throughout the Skeena and Stikine Rivers and in isolated and landlocked populations in the headwaters of the Liard, Peace and Fraser Rivers. How they came to live in those rivers is the subject of the fascinating field of study called zoogeography.

There are many different types of Dolly Varden that are distinguished by where they live. One type lives only in streams, which are often very steep and small. This form is usually quite small. Other forms migrate between lakes and streams or migrate within larger rivers. One type is anadromous like the Pacific salmon. Anadromous Dolly Varden spawn in freshwater but grow and mature in the ocean. Unlike the salmon, anadromous Dolly Varden live in the estuary of their home stream and spend only a few summer months there.

Dolly Varden resemble other trout and char, especially the bull trout with which they are frequently confused. They have an elongated and moderately compressed body. In their marine phase, they have a dark blue or olive-coloured back, silvery sides and a white belly. Like all char they have light coloured yellow, pink or orange spots on a dark background. Trout have dark spots on a light background. In their freshwater spawning phase, males become much darker on their dorsal side, and their flanks glow a brilliant red. Males grow to about 45 centimetres and females to about 35 centimetres. They live up to eight years.