By the time Giovanni was seventeen years old, he decided on his career. Upon reaching maturity he moved to Dieppe, France, after 1506, to pursue a maritime career. He learned his first lessons sailing a ship. Around 1508, at the age of twenty-two, he started on his first expedition to America. He went on the ship La Pensee accompanied with Captain Thomas Aubert. During a fishing trip, he made his solo explorations. He explored Newfoundland, St. Lawrence River, and made several voyages to the eastern Mediterranean. This adventure also provided the basis for his continued interest in the explorations of America.
In 1523 competition in trade was becoming urgent. The French monarchs were seeking new trade routes to Asia. Everyone still believed they could reach the Indies by sailing westward. It was in the 1500s that France, Italy, and England began their explorations. Even though France was a little late in arriving to the new world, the men they sent out were "truly pathfinders and trailblazers." King Francis I of France asked Giovanni to explore Newfoundland and Florida with the goal of finding a sea route to the Pacific Ocean. Within months, Giovanni left with captain Antoine de Conflans with four ships sailing to the Grand Banks of Newfoundland. Two ships were lost to storms and violent seas. The remaining ships were damaged and were forced to return to Brittany, France.
A year later they set sail again. On March 1, 1524 he reached Pamlico Sound and firmly believed it was the entrance to the Pacific Ocean and that easily led to Asia. This report was wrong and would cause many errors on maps. This by any means did not suggest that Giovanni wasn't intelligent. He would keep a logbook, his "little book" that was kind of a great tool. In his logbook he recorded longitudes and latitudes as well as his progress and daily sun observations. Later his logbook disappeared and was never found. Historians say the logbooks' disappearance was an important loss to the history of navigation. The logbook could have been another source to Giovanni's expeditions.