The crust’s fourth most abundant element, iron, barely sticks around in the surface ocean. Yet even small pulses of this essential micronutrient support blooms of phytoplankton and vibrant food webs and fisheries. Where does this iron come from, what happens to it once deposited in the ocean, and what are the consequences for the biogeochemical cycles of macronutrients (N, P, Si) and carbon? In this talk, I explore the sources, sinks, and cycling of iron in disparate productive coastal regions of the ocean. I will discuss research where I have examined the effects of insufficient iron supply on diatom communities within zones of upwelling. I will then pivot to discuss ongoing and future research exploring potential signatures of iron transformation by microbes overcoming challenges of ocean anemia and speculate on what this means for glacial weathering inputs to high latitudes.