Final answer:
Jacques Cartier was the explorer who discovered the St. Lawrence River and Gulf, claiming Canada for France. Samuel de Champlain also played a crucial role in establishing French influence in the region by founding Quebec. Their ventures marked the beginning of French colonization in the vast territories now known as Canada.
Step-by-step explanation:
The explorer who gave France a claim to Canada when he discovered the St. Lawrence River and Gulf was Jacques Cartier. In 1534, Cartier sailed to what is now known as the Gulf of Saint Lawrence, making his marking for France. His discoveries along the St. Lawrence Seaway laid the foundation for French claims and subsequent settlements in Canada, such as Charlesbourg-Royal, the first French settlement in the New World established by Cartier himself. Years later, Samuel de Champlain further solidified France's presence in the region by founding Quebec in 1608, cementing New France and kickstarting French colonial influence in North America.
Cartier's and Champlain's expeditions set in motion a deep history of French and Indigenous relations, particularly with the Algonquian people. The French engaged heavily in the fur trade and were the first European power to colonize the vast regions of what is present-day Canada, claiming territories that included the St. Lawrence River valley, the Great Lakes region, and extending as far south as the Gulf of Mexico. Although control of these vast lands changed hands following the French and Indian War when the British assumed control, the legacy of French Canada remains significant.