Mackenzie’s first expedition was based on maps and assumptions made by North West Company partner Peter Pond, who believed the river flowing from Great Slave Lake connected to “Cook’s Inlet,” a potential Pacific entry point to the inland river systems. Proceeding from the Athabasca Station, Mackenzie, his cousin, and a small party of voyageurs set off in search of a route to the Pacific on June 3, 1789. They paddled Great Slave Lake and what is now known as the Mackenzie River. After following the river’s sharp northward turn, they discovered that the Mackenzie emptied into the Arctic and decided to return to the trading outpost.
In 1792, Mackenzie headed west again on his second expedition in search of a Northwest Passage. He gathered the expedition at Fort Chipewyan, at the junction of the Peace and Smoky Rivers in what is now Alberta. They set off on May 9, 1773, following the Peace River, a tributary of the Mackenzie River. They ascended the Parsnip River and the small network of streams leading to the pass through the Rocky Mountains. After reaching the pass, the expedition canoes followed a westward course, again using streams and lakes. They traversed the Giscome Portage and descended along the McGregor River in order to reach the Fraser River. Mackenzie decided to leave the Fraser and proceeded along the Bella Coola River, eventually emerging at North Bentinck Arm, near Dean Channel, on July 21, 1793. The expedition quickly resumed the journey, returning eastward that summer to arrive at Fort Chipewyan on August 24, 1793.