Military underground port - underground means a military underground port for the combat development of naval forces, equipped with arranged moorings, which ensures the stay of ships, shelters for the crew, their regular maintenance and crew training for the purpose of maintaining the level of combat readiness or readiness for the execution of planned and unplanned tasks, protection from action enemy attacks, protection from hydrometeorological disasters and logistical support with reliance on the logistics units of the Armed Forces of the Republic of Croatia or economic factors of the narrow or wider area.