This package provides a high-level R interface to Unidata's netCDF data files, which are portable across platforms and include metadata information in addition to the data sets. Using this package netCDF files can be opened and data sets read in easily. It is also easy to create new netCDF dimensions, variables, and files, or manipulate existing netCDF files. This interface provides considerably more functionality than the old "netCDF" package for R, and is not compatible with the old "netCDF" package for R.