The paper elaborates on national provisions regulating the conduct of safety and administrative investigations for marine casualties and incidents in the Republic of Croatia. On 5 November 2015, the Government of the Republic of Croatia adopted the Regulation on the Methods and Conditions for Conducting Safety Investigation of Marine Casualties and Incidents, which transposes in the legal order of the Republic of Croatia Directive 2009/18/EC of the European Parliament and of the Council of 23 April 2009 establishing the fundamental principles governing the investigation of accidents in the maritime transport sector and amending Council Directive 1999/35/EC and Directive 2002/59/EC of the European Parliament and of the Council. The conducting of administrative investigation in the Republic of Croatia is regulated by the Ordinance on the Methods, Requirements and Powers for Conducting Administrative Investigation of Marine Casualties enacted in 2016. Unlike safety investigation, administrative investigation is conducted to collect evidence and data for detecting the perpetrator of a maritime accident and to ascertain his/her misdemeanour and criminal responsibility. The authors present the outcomes of safety and administrative investigation procedures to effectively establish the circumstances and causes of such casualties and incidents for the purpose of improving maritime safety and reducing the risk of future casualties involving passenger ships and preventing pollution from ships.