Passage: Kriegsmarine Commander of Submarines (Befehlshaber der U-Boote) Karl Dönitz devised a plan to attack Scapa Flow by submarine within days of the outbreak of war. Its goal would be twofold: first, that displacing the Home Fleet from Scapa Flow would slacken the British North Sea blockade and grant Germany greater freedom to attack the Atlantic convoys; second, the blow would be a symbolic act of vengeance, striking at the same location where the German High Seas Fleet had surrendered and scuttled itself following Germany's defeat in the First World War. Dönitz hand-picked Kapitänleutnant Günther Prien for the task, scheduling the raid for the night of 13/14 October 1939, when the tides would be high and the night moonless.Dönitz was aided by high-quality photographs from a reconnaissance overflight by Siegfried Knemeyer, (who received his first Iron Cross for the mission), and which revealed the weaknesses of the defences and an abundance of targets. He directed Prien to enter Scapa Flow from its east via Kirk Sound, passing to the north of Lamb Holm, a small low-lying island between Burray and Mainland. Prien initially mistook the more southerly Skerry Sound for the chosen route and his sudden realisation that U-47 was heading for the shallow blocked passage forced him to order a rapid turn to the northeast. On the surface, and illuminated by a bright display of the aurora borealis, the submarine threaded between the sunken blockships Seriano and Numidian, grounding itself temporarily on a cable strung from Seriano. It was briefly caught in the headlights of a taxi onshore, but the driver raised no alarm. On entering the harbour proper at 00:27 on 14 October, Prien entered a triumphant Wir sind in Scapa Flow!!! in the log and set a south-westerly course for several kilometres before reversing direction. To his surprise, the anchorage appeared to be almost empty; unknown to him, Forbes' order to disperse the fleet had removed some of the biggest targets. U-47 had been heading directly towards four warships,...

Question: What is one flammable liquid stored in the ship?
kerosene