On his return to Canada, in the spring of 1613, Champlain decided to explore the western waters of Canada. L'Escarbot, who published his "New France," soon after his return from Acadia, tells us that "Champlain promised never to cease his efforts until he has found there [in Canada] a western or northern sea opening up the route to China which so many have so far sought in vain." While at Paris, during the winter of 1612, Champlain saw a map which gave him some idea of the great sea which Hudson had discovered. At the same time he heard from a Frenchman, Nicholas de Vignau, who had come to Paris direct from the Ottawa valley, that while among the Algonquin Indians he had gone with a party to the north where they had found a salt water sea, on whose shores were the remains of an English ship. The Indians had also, according to Vignau, brought back an English lad, whom they intended to present to Champlain when he made his promised visit to the Upper Ottawa.

Champlain probably thought he was at last to realise the dream of his life. Accompanied by Vignau, four other Frenchmen, and an Indian guide, he ascended the great river, with its numerous lakes, cataracts, and islets. He saw the beautiful fall to which ever since has been given the name of Rideau—a name also extended to the river, whose waters make the descent at this point—on account of its striking resemblance to a white curtain. Next he looked into the deep chasm of mist, foam, and raging waters, which the Indians called Asticou or Cauldron (Chaudière), on whose sides and adjacent islets, then thickly wooded, now stand great mills where the electric light flashes amid the long steel saws as they cut into the huge pine logs which the forests of the Ottawa yearly contribute to the commerce and wealth of Canada. At the Chaudière the Indians evoked the spirits of the waters, and offered them gifts of tobacco if they would ward off misfortune. The expedition then passed up the noble expansion of the river known as the Chats, and saw other lakes and cataracts that gave variety and grandeur to the scenery of the river of the Algonquins, as it was then called, and reached at last, after a difficult portage, the country around Allumette lake, where Nicholas de Vignau had passed the previous winter. Two hundred and fifty-four years later, on an August day, a farmer unearthed on this old portage route in the district of North Renfrew, an old brass astrolabe of Paris make, dated 1603; the instrument used in those distant days for taking astronomical observations and ascertaining the latitude. No doubt it had belonged to Champlain, who lost it on this very portage by way of Muskrat and Mud lakes, as from this place he ceases to give us the correct latitudes which he had previously been able to do.

Champlain's lost astrolabe.

Among the Algonquin Indians of this district, who lived in rudely-built bark cabins or camps, and were hunters as well as cultivators of the soil, he soon found out that there was not a word of truth in the story which Nicholas de Vignau had told him of a journey to a northern sea, but that it was the invention of "the most impudent liar whom I have seen for a long time." Champlain did not punish him, though the Indians urged him to put him to death.

Champlain remained a few days among the Indians, making arrangements for future explorations, and studying the customs of the people. He was especially struck with their method of burial. Posts supported a tablet or slab of wood on which was a rude carving supposed to represent the features of the dead. A plume decorated the head of a chief; his weapons meant a warrior; a small bow and one arrow, a boy; a kettle, a wooden spoon, an iron pot, and a paddle, a woman or girl. These figures were painted in red or yellow. The dead slept below, wrapped in furs and surrounded by hatchets, knives, or other treasures which they might like to have in the far-off country to which they had gone; for, as Champlain says, "they believe in the immortality of the soul."

Champlain made no attempt to proceed further up the river. Before leaving the Upper Ottawa, he made a cedar cross, showing the arms of France—a custom of the French explorers, as Cartier's narrative tells us—and fixed it on an elevation by the side of the lake. He also promised Tessouat to return in the following year and assist him against the Iroquois.

The next event of moment in the history of the colony was the arrival in 1615 of Fathers Denis Jamay, Jean d'Olbeau, and Joseph Le Caron, and the lay brother Pacifique du Plessis, who belonged to the mendicant order of the Recollets, or reformed branch of the Franciscans, so named from their founder, St. Francis d'Assisi. They built near the French post at Quebec a little chapel which was placed in charge of Father Jamay and Brother Du Plessis, while Jean d'Olbeau went to live among the Montagnais and Joseph Le Caron among the Hurons of the West.

During the summer of 1615 Champlain fulfilled his pledge to accompany the allied tribes on an expedition into the country of the Iroquois. This was the most important undertaking of Champlain's life in Canada, not only on account of the length of the journey, and the knowledge he obtained of the lake region, but of the loss of prestige he must have sustained among both Iroquois and Canadian Indians who had previously thought the Frenchman invincible. The enemy were reached not by the usual route of the Richelieu and Lake Champlain, considered too dangerous from their neighbourhood to the Iroquois, but by a long detour by way of the Ottawa valley, Georgian Bay, Lake Simcoe, and the portages, rivers, and lakes that lead into the River Trent, which falls into the pretty bay of Quinté, at the eastern end of Lake Ontario, whence they could pass rapidly into the country of the Five Nations.