The Modular Ocean Model, MOM6
MOM6 is the latest version of the MOM models and is under active development. If you are looking for the previous generation ocean model from GFDL, then you might be looking for MOM5, which is supported at https://mom-ocean.github.io. You can read more about the GFDL ocean models at http://www.gfdl.noaa.gov/ocean-model.
MOM6 documentation can be found in several key locations: