Mackenzie was now at the very delta of the great river, where it discharges its waters, broken into numerous and intricate channels, into the Arctic ocean. On Sunday, July 12, the party encamped on an island that rose to a considerable eminence among the flat and dreary waste of broken land and ice in which the travellers now found themselves. The channels of the river had here widened into great sheets of water, so shallow that for stretches of many miles, east and west, the depth never exceeded five feet. Mackenzie and 'English Chief,' his principal follower, ascended to the highest ground on the island, from which they were able to command a wide view in all directions. To the south of them lay the tortuous and complicated channels of the broad river which they had descended; east and north were islands in great number; but on the westward side the eye could discern the broad field of solid ice that marked the Arctic ocean.
Mackenzie had reached the goal of his endeavours. His followers, when they learned that the open sea, the mer d'ouest as they called it, was in sight, were transformed; instead of sullen ill-will they manifested the highest degree of confidence and eager expectation. They declared their readiness to follow their leader wherever he wished to go, and begged that he would not turn back without actually reaching the shore of the unknown sea. But in reality they had already reached it. That evening, when their camp was pitched and they were about to retire to sleep, under the full light of the unsinking sun, the inrush of the Arctic tide, threatening to swamp their baggage and drown out their tents, proved beyond all doubt that they were now actually on the shore of the ocean.
For three days Mackenzie remained beside the Arctic ocean. Heavy gales blew in from the north-west, and in the open water to the westward whales were seen. Mackenzie and his men, in their exultation at this final proof of their whereabouts, were rash enough to start in pursuit in a canoe. Fortunately, a thick curtain of fog fell on the ocean and terminated the chase. In memory of the occurrence, Mackenzie called his island Whale Island. On the morning of July 14, 1789, Mackenzie, convinced that his search had succeeded, ordered a post to be erected on the island beside his tents, on which he carved the latitude as he had calculated it (69° 14' north), his own name, the number of persons who were with him and the time that was spent there.
This day Mackenzie spent in camp, for a great gale, blowing with rain and bitter cold, made it hazardous to embark. But on the next morning the canoes were headed for the south, and the return journey was begun. It was time indeed. Only about five hundred pounds weight of supplies was now left in the canoes—enough, it was calculated, to suffice for about twelve days. As the return journey might well occupy as many weeks, the fate of the voyageurs must now depend on the chances of fishing and the chase.
As a matter of fact the ascent of the river, which Mackenzie conducted with signal success and almost without incident, occupied two months. The weather was favourable. The wild gales which had been faced in the Arctic delta were left behind, and, under mild skies and unending sunlight, and with wild fowl abundant about them, the canoes were urged steadily against the stream. The end of the month of July brought the explorers to the Great Bear river; from this point an abundance of berries on the banks of the stream—the huckleberry, the raspberry and the saskatoon—afforded a welcome addition to their supplies. As they reached the narrower parts of the river, where it flowed between high banks, the swift current made paddling useless and compelled the men to haul the canoes with the towing line. At other times steady strong winds from the north enabled them to rig their sails and skim without effort over the broad surface of the river. Mackenzie noted with interest the varied nature and the fine resources of the country of the upper river. At one place petroleum, having the appearance of yellow wax, was seen oozing from the rocks; at another place a vast seam of coal in the river bank was observed to be burning. On August 22 the canoes were driven over the last reaches of the Mackenzie with a west wind strong and cold behind them, and were carried out upon the broad bosom of the Great Slave Lake. The voyageurs were once more in known country. The navigation of the lake, now free from ice, was without difficulty, and the canoes drove at a furious rate over its waters. On August 24 three canoes were sighted sailing on the lake, and were presently found to contain Leroux and his party, who had been carrying on the fur trade in that district during Mackenzie's absence.
The rest of the journey offered no difficulty. There remained, indeed, some two hundred and sixty miles of paddle and portage to traverse the Slave river and reach Fort Chipewyan. But to the stout arms of Mackenzie's trained voyageurs this was only a summer diversion. On September 12, 1789, Alexander Mackenzie safely reached the fort. His voyage had occupied one hundred and two days. Its successful completion brought to the world its first knowledge of that vast waterway of the northern country, whose extensive resources in timber and coal, in mineral and animal wealth, still await development.