From FVCOM Wiki
FVCOM output can be visualized using the free VisIt Visualization software from LLNL using a plugin developed by D. Stuebe. Binaries for OS X and Windows and some distributions of Linux are available. You may also build visit yourself from source. VisIt is a very powerful visualization engine designed to handle very large datasets.
is a commercial product for OS X. The author has developed a plugin to visualization directly from the FVCOM NetCDF output files. Using scripts, Datatank has practically all the capabilities as VisIt with higher quality graphics and movies. These include transects, contours, point probes, line probes, etc. A tarfile containing a sample script and simple NetCDF file can be downloaded here.
Screenshot of Datatank in Use