This paper thoroughly describes the data processing steps and assessment of the usefulness of the new SWOT mission for advancing ocean science. The paper will be of great interest the ocean and sea ice communities and others. The discussion of the benefits, relevance, and limitations of Level-3 swath-altimeter products for various research domains is particularly important.

This is an original study on a on a coastal ecosystem, combining environmental data with data on phytoplankton functional groups. Such a time series on flow cytometry in combination with environmental data at high temporal resolution over multiple years is relatively rare and can give a detailed view into the variability of the phytoplankton community over the last decade. This is the first pluri-annual study of the whole size-range of the phytoplankton community characterized by one unique method.

The paper demonstrates how oceanographic parameters, like Sea Level Anomaly, surface currents and vorticity, from remote sensing are improved when SWOT (Surface Water Ocean Topography) data are included.

The use of neural networks to emulate the dynamics of the Earth system (ocean, atmosphere) is of critical importance since it enables efficient and operational forecast, data assimilation, and affordable uncertainty quantification. This field has been very productive in numerical weather forecasts but relatively fewer results were demonstrated in the oceans. This paper could be a reference for mesoscale ocean dynamics emulation.

This study is based on observations from the new swath altimetry satellite SWOT. It is the first to describe and characterise internal tides using this new altimetry mission. It therefore highlights the 2D potential of SWOT and opens up new prospects for studying the variability of the internal tide.

Marine heatwaves are of particular interest globally currently, both scientifically and for their impact on communities. While much work has been done on surface expressions of marine heatwaves, their subsurface expressions have been less well studied. This is particularly the case in the Southwest Indian Ocean. This region is climatically important and the ecological impacts of marine heatwaves (both surface and subsurface) in this area could be significant, with consequential negative socio-economic outcomes.

This is the first in-situ validation of the reanalysis atmospheric flux and observations. Given the importance of the region in the context of global sea-level rise and recent advancements of numerical models at ice-ocean-atmosphere interface, the problems identified and the new parameterization in this paper make a difference.

It is shown that newly available geodesy combined with suitably located coastal tide gauges is accurate enough for validating model predictions of coastal mean dynamic topography (MDT). Moreover, alongshore differences of MDT can provide estimates of (1) average alongshore current and (2) area-integrated nearshore circulation. Thereby estimates of MDT from geodesy and tide-gauges have value for ocean monitoring.

This paper is of high quality, it exemplifies the complexity of detecting ocean eddies (eulerian versus lagrangian, importance of the code parameters of the regions considered), it acknowledges the fact that not all ocean eddies are the same (dynamically talking), and that their effect on plankton is complex. The method presented is well-described, powerful and would allow digging into these biophysical interactions in many different oceanographic settings. It shows that the common view following seminal papers by e.g. McGillicuddy and D. Chelton that consists of "cyclonic eddies -> isopycnals shaoling -> increase phytoplankton biomass" versus "anticyclonic eddies -> isopycnal deepening -> decreased phytoplankton biomass" is too simplistic and needed to be updated.

This paper highlights a new implementation of density co-ordinate functionality within an adjoint ocean model, the MITgcm ECCO adjoint. This is illustrated accordingly with a science application investigating the variability of Subantarctic Mode Water. The use of adjoints helps to trace causal links within the ocean, and the density-following feature is of particular interest for the ocean community with many possible further applications.

The authors present the first synoptic characterisation of an oceanic mesoscale eddy’s full life cycle using groundbreaking SWOT satellite altimetry. This unprecedented view challenges the long-standing perception of eddies as simple, elliptical structures, revealing the crucial role of mesoscale interactions in their evolution. The SWOT results capture intense submesoscale turbulence at the eddy’s rim, exposing secondary instabilities that likely drive its dissipation. These findings not only validate decades of vortex theory but also open new frontiers in our understanding of oceanic turbulence.