The Southern Ocean Time Series acquires observations in subantarctic waters south of Australia. We present the seasonality in hydrography, biogeochemistry, phytoplankton community composition, and particulate organic and inorganic carbon export to the deep sea using observations collected between 1997 and 2022. We also review recent research underpinned by these observations and emphasize the value of long time series for understanding ocean processes and responses to a changing climate.