Ren矇-Robert Cavelier, Sieur de La Salle, or Robert de La Salle (November 22, 1643 - March 19, 1687) was a French explorer. He explored the Great Lakes region of the United States and Canada, the Mississippi River, and the Gulf of Mexico. Father Jacques Marquette (June 1, 1635 - May 18, 1675) was a French Jesuit missionary and explorer.In 1673, he joined the expedition of Louis Jolliet, a French-Canadian explorer. The Joliet-Marquette expedition traveled to within 435 miles of the Gulf of Mexico but turned back at the mouth of the Arkansas River, for fear of encountering explorers or colonists from Spain. Father Louis Hennepin (May 12, 1626 - 1705) was a Roman Catholic priest and missionary of the Franciscan Recollet order and an explorer of the interior of North America. Hennepin was part of an advance party to search for the Mississippi River.