This manuscript topographic map shows the main outlet of the Amazon River into the Atlantic Ocean. The river's estuary is more than 330 kilometers wide. Early explorers called it the “sweet sea” because of the vast amount of fresh water pouring into the ocean. The map is the work of João Vasco Manuel de Braun, a Brazilian of English descent who served as governor of Macapá, the equatorial region in which the mouth of the Amazon is located. Amazon River; Brazil -- History -- Colonial Period, 1500-1822; Rivers