The Amazon Reef (also referred to as the Amazonian Reef) is an extensive coral and sponge reef system, located in the Atlantic Ocean off the coast of French Guiana and northern Brazil. It is one of the largest known reef systems in the world, with scientists estimating its length at over 970 kilometres (600 miles), and its area as over 9,300 km2 (3,600 sq mi). Publication of its discovery was released in April 2016, following an oceanographic study of the region in 2012. Evidence of a large structure near the delta of the Amazon River dated from as early as the 1950s.