Land-based volcanic systems and geophysical modelling of mid-ocean ridges suggest that submarine volcanic activity may be influenced by glacially driven changes in sea level. Is there evidence for glacially-paced variation in submarine hydrothermal circulation? In this talk, I will present a suite of hydrothermal iron flux records derived from mid-ocean ridge sediment cores and explore their implications for marine iron cycling, iron delivery to Southern Ocean surface waters, and possible driving mechanisms linking the climate system and the solid Earth on glacial timescales. I will also elaborate on the utilization of constant flux proxies, the geochemical tools that enable reconstruction of hydrothermal time series and other paleoceanographic flux records from sediments that have accumulated in complex bathymetric environments.