Processes above and below the water can cause upwelling at the coast and at places in the ocean. This leads to significant phytoplankton activity, and the resultant food web is the source of many of our fisheries. Only a few isolated studies have focussed on upwelling in Aotearoa NZ; much of what we know comes from this, together with knowledge from similar situations world-wide. Often upwelling is inferred from observations of cool water near the coast. NZASE Science Communicator Mike Stone investigates the process and its implications.