<Tr> <Th> Ocean / sea sources </Th> <Td> North Atlantic Ocean </Td> </Tr> <Tr> <Th> Managing agency </Th> <Td> Department of Natural and Environmental Resources, Puerto Rico Ports Authority </Td> </Tr> <P> San Juan Bay (Spanish: Bahía de San Juan) is the inlet adjacent to Old San Juan in northeastern Puerto Rico . It is the largest body of water in an estuary of about 150 square miles (390 km) of channels, inlets and eight interconnected lagoons . Puerto Rico's deepest bay contains the island's busiest harbor, and since 1508 it has been historically significant . </P> <P> The bay is a semi-enclosed body of water with an elaborate system of loops, basins and channels at the center of Puerto Rico's most significant historical monuments and largest communities . San Juan Bay provides recreation, sightseeing and tourist attractions, and its curved shape offers a variety of docking facilities for watercraft . Because of commercial expansion and environmental stress on the region, the estuary has been the focus of restoration ecology projects . In 2015, the San Juan Estuary Program (Programa del estuario de la Bahía de San Juan) began using green flags to mark the condition of the bay's waters . </P>

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