in these observations. As noted earlier, an important theme of research at NIO has been understanding the oceanography of the North Indian Ocean – a tropical and small basin driven by strongly seasonal winds. The uppermost 200 m (oceans are on average about 4000 m deep) form the most active portion of the ocean. Here, major currents are forced by winds, and primary producers (microscopic plants that drift with currents) set the stage for intricate interactions that go across the traditional boundaries between disciplines, leading to a new discipline, biogeochemistry of the oceans. Some of NIO's most cited research contributions have been about two aspects of the upper layer: its circulation and biogeochemistry. Currents in this layer are driven by winds. As these are periodic over the North Indian Ocean, so are the currents, in striking contrast to other tropical regions of the world. The link between the winds and currents, however, is rather intricate. NIO researchers played a leading role in defining the nature of seasonality in the currents over the basin in general, and along the coast of India in particular. Subsequent analysis and model studies showed that the circulation of the North Indian Ocean needs to be looked at holistically across the basin because the winds at a location influence not only the local current, but affect the current at remote locations at a later time owing to the propagation of large-scale waves. For example, it is now known that the winds along the Indian east coast significantly affect the seasonal cycle of the current off the Indian west coast. By restricting the North Indian Ocean to south of 25° N, the Asian landmass prevents the basin from having access to the sub-tropical convergence zone, a region that usually occurs at a latitude of about 40° and is an important supplier of oxygen to the ocean. Not having access to such a regime, the North Indian Ocean is starved of oxygen. Another reason why oxygen is low is the consequence of high concentration of the primary producers of the region. When these plants and zooplankton that feed on them die and sink they get microbially degraded, thus consuming oxygen. NIO researchers have played a major role in answering critical questions concerning the processes that go on in this basin with lower than normal oxygen levels. Some of the questions that have been addressed are the following: Does