A dramatic and previously unknown watercolour scene of Canada — painted during the golden age of Arctic exploration by that era's most legendary artist — has come to light in Britain after 175 years.

The image of an enormous iceberg towering above the famous Arctic expedition ship HMS Terror and one of its rowboats was painted by Royal Navy artist-turned-admiral George Back, who captained the vessel during a trouble-plagued voyage to Hudson Bay in 1836.

The painting, which has emerged from the obscurity of a Back family collection to be auctioned in London by Bonhams, is expected to fetch up to $25,000 at a maritime art sale in September.

By then, the very ship depicted in Back's long-lost painting may have been located lying on the Arctic seabed in western Nunavut.

Parks Canada announced earlier this month that it will undertake a new search in August to locate the lost ships of the Franklin Expedition — the Terror and its sister vessel HMS Erebus, which were sunk by pack ice during a disastrous voyage led in the 1840s by Back's friend and mentor, Sir John Franklin.

"This is a fascinating painting by an explorer whose names ranks alongside pioneer explorers such as Sir John Franklin and John Ross," said Bonhams maritime art specialist Alastair Laird.

Researchers believe the painting dates from July 1836, when Back described in his diary the Terror's encounter with a colossal iceberg off the southeast coast of Baffin Island.

"We observed an enormous berg, the perpendicular face of which was not less than 300 feet high," Back wrote at the time. He also noted that he sent several crewmen in one of the ship's lifeboats "to procure fresh water from the pools formed on the surface" of the floating mountain of ice.

Massive icebergs regularly track a course south down Davis Strait between Baffin Island and the west coast of Greenland, where most originate after breaking off from glaciers. The iceberg struck by the Titanic east of Newfoundland in 1912 would have followed this route to southern waters.

Back was a frequent visitor to the Canadian North in the first half of the 19th century. An avid chronicler of his journeys as well as a skilled and prolific field artist, his collected works constitute this country's most important visual record of the British voyages that — along with the region's long-standing occupation by the Inuit — are the foundation of Canada's Arctic sovereignty.

Back's command of the HMS Terror expedition of 1836-37 was fraught with difficulty, and the badly-damaged ship barely made it back to Britain after a perilous summer voyage through unusually ice-choked Arctic waters.

The loss of the same vessel under Franklin's command a decade later brought an end to one of the most storied ships in British and Canadian history.

Remarkably, the Terror — launched from a shipyard in southwest England in 1813 — also played a notable role in American history. It was one of the British ships involved in the War of 1812 bombardment of Baltimore's Fort McHenry, an attack recounted in rich detail in Francis Scott Key's lyrics for the U.S. national anthem.

"HMS Terror's significance is certainly enhanced with this participation in the events at Baltimore," Marc-Andre Bernier, Parks Canada's chief of underwater archeology, told Postmedia News last year.

Along with HMS Erebus, Bernier said at the time, the Terror "is considered one the most significant ships in the history of the exploration of Canada's North."

After two major sweeps of the Arctic sea floor in 2008 and 2010, Parks Canada and its partner agencies have narrowed next month's search for the Franklin ships to a relatively small area near Nunavut's King William Island.