High Quality Content by WIKIPEDIA articles! Biscayne Bay is a lagoon that is approximately 35 miles long and up to 8 miles wide located on the Atlantic coast of south Florida, United States. It is usually divided for purposes of discussion and analysis into three parts: North Bay, Central Bay and South Bay. North Bay lies between Miami Beach barrier island from Miami on the mainland. It has been severely affected over the last century by raw sewage releases, urban runoff, shoreline bulkheading, dredging, the creation of artificial islands and the loss of natural fresh water flow into the bay. However, water quality has steadily improved since regular monitoring began in 1979. North Bay accounts for only 10% of the water area of the bay.