In “No Man’s River” (Carroll & Graf, $25), Farley Mowat, one of Canada’s most important literary figures and author of 38 books, offers yet another minor masterpiece of the type we have come to expect from him.

Mowat writes about his post-World War II visit to the frozen, barren lands west of Hudson Bay as part of a two-man scientific expedition with an eccentric and irascible American naturalist, who soon fired him.

Mowat, now 81, had been from his earliest days an avid outdoorsman and nature lover, a collector of eggs, birds, dogs, coyotes and other sundry wildlife in Saskatchewan.

At 15, he was taken by a great-uncle on a six-week specimen-gathering expedition to the Barrens, an experience that more or less set his future course.

When World War II broke out, Mowat joined Canada’s army and served four years in Italy and northeastern Europe. Back home again, he found it difficult to settle down in a metropolitan region and to decide what career to pursue in a university, so he sought and found employment that would take him to the frozen North he had grown to love.

In 1947, Mowat traveled to Churchill, Manitoba, and then to Nueltin Lake with his American boss. The aim of this venture, called the Keewatin Zoological Expedition, was to collect and record specimens of all types of wildlife.

Mowat by then had had enough of killing during his war experiences and was soon at odds with his boss. Their disagreements led to an early and acrimonious parting of the ways.

By this time, Mowat had befriended Charles Schweder, a trapper born to a German father and Cree Indian mother. Schweder detested urban life and felt himself to be a native of the frozen northern wastelands.

When he met Mowat, Schweder was about to make a long trip to outlying areas to take supplies to natives who were starving and were succumbing to smallpox.

Mowat accompanied Schweder, and “No Man’s River” offers a journal of their six months of sledding, canoeing and plodding in the remote areas of northwestern Manitoba and Nunavut (formerly the Northwest Territories).

They crowned their travels by becoming the first on record to descend the “Big River” (the “Thliewasa” to the natives), from its origins in Nueltin Lake to its outflow into Hudson Bay. The Hudson Bay Inuit navigated only fairly short distances upriver and had no recollection of anybody ever having come by canoe in the opposite direction.

Mowat then began his literary career, writing his first books on the plight of the natives, whose welfare was ignored by Canadian government authorities.

Mowat’s many narratives of the life of the natives of the Canadian North created a furor over the years and have contributed to a much greater national knowledge and awareness of these ancient and primitive peoples, whose numbers have declined drastically.