Oceans are an integral constituent of the coupled earth system that has atmosphere and earth as the two other components. Apart from modulating the climate world over, the oceans play a significant role in carbon sequestration and producing enough oxygen through phytoplankton for inhabitants of the Earth. Our ancient scriptures mention ‘samundra-manthan’ or the churning of the ocean that provided objects of immense wealth, including elixir. The oceanographic surveys in last fifty years or so have confirmed that oceans indeed are life-savers/providers and are storehouse of energy, food and mineral resources that are capable of sustaining life. The current special issue 4 (no. 115) of Geography and You on oceans is timely as we are in the midst of International Indian Ocean Expedition-2 (IIOE-2) with background of years of intensive exploration of Indian and Southern Oceans. An overview of the science programme of IIOE-2 details the structure and envisages experiments that will further advance our understanding of the complex phenomenon of ocean-atmosphere interaction, monsoons etc. The well researched articles by subject experts on deep sea fishery resources, sea level rise, ocean pollution, phytoplankton bloom and the technicalities of Polar Research Vessel have touched various domains of exploration, exploitation and climate change perspectives of ocean research.