The Human and Engineered Systems (HES) team is in the process of finalizing the configuration for upcoming E3SM version 3 simulations.  There have been a number of substantial changes to the marine biogeochemistry (BGC) capabilities in E3SM since the 2019  release of version 1.1.  Although there were no fully coupled production simulations using marine BGC based on E3SM version 2, a major change was made during this time by replacing the ported version of the Biogeochemical Elemental Cycling (BEC) code with the Marine Biogeochemical Library (MarBL).  Quite a few enhancements and improvements have since been added to E3SM in preparation for the version 3 simulation campaign.  Our poster will highlight many of these developments, including more realistic river nutrient inputs, different vertical diffusivity for passive (compared to active) tracers, passive tracer supercycling, and parameter tuning.  We will also discuss model spinup strategies, and modifications that are still necessary before beginning the production simulations.