 The reef's area extends as far as offshore, and is estimated to lie in waters ranging from deep.The reef's existence is unusual, as reef systems do not often exist in the mouths of larger rivers like the Amazon, due to the low salinity and high acidity, in addition to the continuous rain of sediments.Before the reef's discovery, it was originally believed that the Amazon, with its sediment-rich plume, represented a significant gap in reef distribution across the Western Atlantic, correlating with the accepted view that corals thrived in clear waters along tropical shelves.