Unidata's network Common Data Form, netCDF, provides users with an efficient set of software for scientific-data-storage, retrieval, and manipulation. The netCDF file format is machine-independent, direct-access, self-describing, and in the public domain, thereby alleviating many problems associated with accessing output from large hydrodynamic models. NetCDF has programming interfaces in both the Fortran and C computer language with an interface to C++ planned for release in the future. NetCDF also has an abstract data type that relieves users from understanding details of the binary file structure; data are written and retrieved by an intuitive, user-supplied name rather than by file position. Users are aided further by Unidata's inclusion of the Common Data Language, CDL, a printable text-equivalent of the contents of a netCDF file. Unidata provides numerous operators and utilities for processing netCDF files. In addition, a number of public-domain and proprietary netCDF utilities from other sources are available at this time or will be available later this year. The U.S. Geological Survey has produced and is producing a number of public-domain netCDF utilities.