The instrumented sea-mammals program is the global network of open-ocean in-situ observations, being implemented by an international partnership of researchers. Instrumented sea-mammals provide trajectories and vertical profiles of various physical, biogeochemical variables in different regions around the globe. The program’s objective is to build and maintain a multidisciplinary global network for a broad range of research and operational applications including biology, climate and ecosystem variability and forecasting and ocean state validation. Sea-mammals data are publicly available. More information about the project is available at: http://www.coriolis.eu.org/Observing-the-Ocean/Marine-Mammals The main purpose of this document is to specify the format of the files that are used to distribute Sea-mammals data, and to document the standards used therein. This includes naming conventions, or taxonomy, as well as metadata content. This document is derived from the “Argo NetCDF user’s manual”, adapted and specialized to Sea-mammals in-situ observations (wheras Argo is specialized in floats ocean observations).