What was Giovanni De Verrazano's main accomplishment?

Giovanni da Verrazzano's main accomplishment was his exploration of the North American coast in the early 16th century, specifically his voyage in 1524 under the French flag. He is credited with being the first European to explore and map significant portions of the Atlantic coastline, including present-day New York Harbor and the areas surrounding it. His expeditions provided valuable information about the geography and indigenous peoples of the region, paving the way for future exploration and colonization.