It had previously been observed by Italian explorer Giovanni da Verrazano sailing for King Francis I of France in 1524 , as he became the first European known to have entered the Upper New York Bay .
Francis I of France considered the river to be an estuary .
It had previously been observed by Italian explorer Giovanni da Verrazano sailing for King Francis I of France in 1524 , as he became the first European known to have entered the Upper New York Bay , but he considered the river to be an estuary .