For this seventh exploration of arctic and subarctic Québec, Jacques Rousseau chooses the Otish Mountains, at their central point where the most modern geographical map of the time puts these small mountains. With few exceptions, no explorer had yet really been in this region whose existence was revealed to cartographers by aircraft traveling in Greenland during the Second War. These mountains are not a chain, but a mass of about 1,200 m high, spanning approximately 20 km by 50 km. At 160-250 km north-east of Lake Mistassini and located approximately at the geographic center of Quebec, the Otish Mountains belong to the Canadian Shield.

For this expedition, Jacques Rousseau is accompanied by René Pomerleau (1904-1993), a mycologist and professor at the University of Montreal, his son François and a native guide Montagnais, Antoine Grégoire.
Climb
Thinking he is climbing the highest peak of the Otish, Rousseau suffer a cardiac arrest, forcing him and his guide to sleep under the stars.

Rousseau later uses the name Watshish as used by Aboriginal people, in a 1959 article in the Cahiers de géographie periodical.