This Users Manual provides an introduction to the MultiMet system and describes the routine procedures for operating the MultiMet system at sea and for processing the data. It consists of three parts: Part A. provides a general introduction to the MultiMet system and describes the hardware; Part B. describes the data processing on NERC ships; Part C. describes the post-cruise processing ( ego for the OWS Cumulus data). Fortran code and UNIX scripts that form part of the appendices following all three sections are supplied on disk. All are text files that can be opened into a word processing package, the scripts can be used (following checking and alteration) after they have been transferred back onto the SUN system using ftp.