The freezer trawler suffered a major failure in the factory freezer equipment, resulting in the entire release of the refrigerant into the engine room, displacing the oxygen and shutting down the main and auxiliary engines. Hours later, the trawler developed a list of about 8° to 10°, increasing to approximately 29° due to an accumulation of seawater on the starboard side. Subsequently, the crew called for assistance and abandoned the trawler. Twenty-five minutes later, she downflooded and sank stern first. Why did it happen? The shutdown of all equipment prevented the operation of the seawater discharge pumps. Screw down non-return valves were partially obstructed by waste debris and the unavailability of anti-syphon loops assisted in the ingress of seawater. Furthermore, weathertight and watertight closures were not effectively sealed against downflooding. What can we learn? The importance of ensuring that are closures are tight against downflooding. Shore Authorities should be alerted during the early stages of the occurrence to ensure timely search and rescue.