ECCO-Darwin is a global ocean biogeochemistry model used to obtain data-constrained estimates of ocean circulation, sea ice, microbial ecology, and biogeochemistry. The model is based on a global-ocean and sea-ice configuration of the Massachusetts Institute of Technology general circulation model (MITgcm), constrained by the Estimating the Circulation and Climate of the Ocean (ECCO) project using nearly all available ocean observations from 1992 to the near-present. This physical circulation estimate is coupled with the MIT Darwin microbial community model, which drives and interacts with marine chemistry and carbon variables. The Darwin ecology and biogeochemistry modules are optimized using a low-dimension estimation approach based on the computation of model Green’s Functions. Together, ECCO and Darwin provide a data-constrained, property-conserving estimate of the three-dimensional, time-evolving physical and biogeochemical ocean state. This presentation discusses recent ECCO-Darwin updates designed to capture the land-ocean aquatic continuum more accurately. These key developments include: (i) the integration of biogeochemical river discharge, (ii) a more realistic representation of bottom sediments, (iii) parameterized estuarine processes, and (iv) the implementation of a radiative transfer model. Collectively, these advancements significantly improve the simulation of coastal dynamics and facilitate robust model evaluation using satellite ocean color observations.