 A new study shows that the world's largest hypoxic anoxic zone along the west coast of India is formed through a natural process called upwelling, which occurs during the summer monsoon season. The extent and persistence of this coastal oxygen deficiency depend on the degree of deoxygenation of source waters for the upwelling. An anoxia is confined to a specific area of the western Indian Shelf where suboxic waters from the core oxygen minimum zone in the Arabian Sea are brought up. This article was authored by G. V. M. Gupta, Arjo Thibabu, C. H. V. Romu and others.