Lake Hazen, the largest lake in the world entirely north of the Arctic Circle (66deg.0min. N), is situated at the northern end of Ellesmere Island, the largest and most northerly of the Queen Elizabeth Islands (1). The lake was first discovered by the Inuit. In modern times it was first discovered in 1882 by Adolphus Greely during his exploration of the region during 1881-1983 (2). Greely established a base at Fort Conger (81!|4'N) as part of the first International Geophysical Year (IGY). During the spring of 1882 he explored Conybeare and Chandler Fjords, moving up the Ruggles River to Lake Hazen. Greely, a signals officer in the U.S. Army, named the lake after his superior, William Babcock Hazen, the chief signals officer who had been responsible for the dispatch of the expedition.

In an earlier period the region had been occupied by Inuit of the Dorset culture, up to about 1200 A. D., but the area was abandoned following the climatic deterioration that began about this time (3) coincident with the spread of the more recent Thule culture.

Lake Hazen is situated on the Palaeozoic rocks of the Hazen Plateau of the Eureka Uplands (4, 5, 6). North of the lake the Hazen Fault Zone forms the boundary of the Grant Land Mountains. These mountains are largely covered by ice although nunataks (a hill or mountain completely surrounded by glacial ice) rise above the permanent ice-fields to heights up to 2,500 m. The icefields feed valley glaciers flowing southward to the Hazen Plateau, the melting of which in summer, primarily the Henrietta Nesmith and the Gilmour Glaciers, forms the major source of water for the lake.

Most of the information on Lake Hazen is derived from the results of a further IGY expedition in 1957-58 (1). In addition to geophysical and meteorological (7, 8) observations, investigations on the surrounding vegetation (9) and its susceptibility to disturbance (10), the lake fauna (11, 12) and the limnology were carried out. A bibliography of Lake Hazen region was prepared by the members of the IGY team (13). Unfortunately, the limnologist of the expedition, Dr. R. E. Deane, was drowned in a boating accident in southern Canada shortly after his return, thus precluding presentation of the full results.

The region around Lake Hazen functions as a "thermal oasis" in a true polar desert, the Lake Hazen Fault Zone functioning as a gigantic solar receiver while Lake Hazen itself augments this effect (7). Air temperatures frequently rise to 10-13!|between June 1 and August 10 although the lake itself remains ice-covered in all but the warmest years (8). Greely (2) reported a shade temperature of 23!|one afternoon in June 1882. The area is extremely dry experiencing only about 25 mm of precipitation annually.

The only fish species present, the anadromous arctic charr Salvelinus alpinus, maintains a sizeable population recognizable as distinct anadromous (migratory) and non-anadromous forms (14). These are the most northerly stock of charr in North America, possibly in the whole world. In recent years a small sport-fishing camp has been operating on the lake, serviced out of Resolute Bay. In 1983 the region was given the protective status of a National Park (5).