The distribution of the Deepwater Sculpin is almost entirely limited to Canada with the exception of the American Great Lakes and a few inland lakes in Michigan and Minnesota. In Canada, its distribution is patchy and limited to cold, deep lakes in areas that were formerly glaciated or with proglacial lake connections. This includes the Gatineau region through the Laurentian Great Lakes, Manitoba and Saskatchewan and northward to Great Bear and Great Slave lakes in the Northwest Territories. An isolated population also exists in Waterton Lake, Alberta. Designated at risk (Special Concern) are the Great Lakes-Western St. Lawrence populations, which are found in only 10 lakes in eastern Canada. In Ontario, this fish occurs in lakes Nipigon, Ontario, Superior, Fairbank, Huron and Erie. In Lake Erie, only larvae (young-of-the-year) have been observed. In Quebec, it occurs in Lac des Iles and in Roddick, Thirty-one-Mile and Heney lakes. Populations in Heney Lake and Lac des Iles are in decline or may even no longer exist.

The Deepwater Sculpin is a lake-dwelling sculpin with a flat, long body averaging 51 to 76 mm in length; maximum length of 235 mm. It has a large mouth with small teeth on both jaws, tongue, and roof of mouth. The Deepwater Sculpin has separated dorsal fins; the first has 7 to 10 spines, the second has 11 to 16 soft rays. It is dark grey to brown in colour with dark saddles marking the back; light speckling on sides and a pale belly. The reproductive cycle is not well understood and the time of spawning is not known. Age of maturity has been estimated at three years for females and two for males.