The purpose of this document is to set out the concepts, data standards, and definitions to be applied when coding data in relation to marine incidents. This document was produced to ensure that consistent and comparable information on such incidents may be collected and used to assist in the formulation, monitoring and measurement of uniform marine safety policy and legislation throughout Australia and New Zealand. This reference manual is for use by marine incident coders, marine investigators and data analysts working in the marine safety area. The National Marine Safety Minimum Data Set and definitions described in this manual apply exclusively to incidents involving recreational and small commercial vessels, (i.e: vessels licensed or surveyed under jurisdictional legislation). Incidents involving trading vessels which require investigation and reporting by the Australian Maritime Safety Authority may use similar data definition and data items to that contained in this reference manual, however, it is not intended to merge the two data sets at this time. The current diversity in the nature of incidents and their investigation between trading ships and recreational and small commercial vessels makes the merging of data collection impractical at this stage.