EXER MARSEC-21 Initial / Main Planning Conference (IPC/MPC) was virtually and successfully conducted on 29 March 2021, and a total of 35 participants representing various maritime interested stakeholders from the military, governmental institutions, and academia attended the proceeding / discussions. The aims of the event were to provide an update for the way-ahead of EXER MARSEC-21 to interested stakeholders and possible target audiences, academia, and supporting COEs, to harmonize views concerning the prepared Scenario Modules, as well as to plot the next steps in the development of a viable scenario product - the foundational basis for the Exercise.