Diver being prepared before assisting in the recovery of the Dutch O-11 submarine, which was rammed by the Hr.Ms. BV 3 tugboat and sank in the port of Den Helder on 6 Mar 1940.
There were 3 officers and 27 crewmen on board at the time. Sergeant L. Logmans, Koksmaat O. Postma and Sergeant F.W.J. Steenvoort were killed in the collision. There was another officer trapped with the three of them, but he managed to survive by clinging to equipment on the highest possible point in the torpedo room. He waited until the inflow of water stopped and then dove through a hole and swam free without even being injured.
It was quite interesting for me personally to do research on this submarine considering I did my STCW basic training in this same port within Den Helder.