Who named the Island “Isle Saint-Jean”? Why this name?

No one really knows, but the name already existed in 1601, since it appeared on a map.

Jacques Cartier did not name the Island.  He had not recognized the insularity of our territory when he docked here at the end of June 1534.

The Island was probably named after Saint-Jean-Baptiste, since explorers docked here around the time of the patronal holiday (June 24).