[seafarer]

By Siem Spruijt, crewmember of the Dutch Submarine O 19.
....
Hardly relieved from watch at four in the morning and just about to get into my bunk, the world seemed to have come to a stand still all of a sudden and I was practically flying through the air and thrown against the bulkhead. A violent shaking of the boat immediately followed. What happened? The sub, doing 18 knots, had struck Ladd Reef, coral reef in the South China Sea submerged due to high tide. The impact was immense. Just imagine 2300 tons and with a speed of 18 kts coming to a complete standstill within 20 meters! The heavy shaking was caused by both diesels full astern while the screw tips where hitting the reef.
...
I will now quote my senior engineer officer Mr. Kiepe (deceased) in technical command:

"..........At low tide it appeared that the boat was grounded at various places around amidships. The CO reported the mishap and requested assistance, whilst the ship's company commenced transferring heavy weights from the forward to the stern of the boat. Water and fuel not needed for the journey to Subic were blown overboard. The anchor and chain dropped on the reef, as did the mines which could be dropped out of their bins.
...
We found a way to make the boat jump, which would hopefully be of use. When a boat has main ballast tanks fitted with Kingstons, the low-pressure turbo blower can be used to put as much pressure in as it can stand. By opening the Kingstons suddenly, the released air makes the boat jump some inches, which should be helpful during pulling. With the USS Cod assisting, the attempt to pull O 19 off had a higher chance of success. The attempt began at high tide, with both diesels running astern at full power, torpedoes being fired from all bow tubes, the gun being fired, the jump-effect being used and the Cod pulling on the screws with her powerful engines. All to no avail, as the O-19 did not move an inch. A smooth hull submarine would have come off I am sure, but O-19 had open mine bins lodged in the reef, making it impossible to shift. A number of attempts were made, all of which were abortive. There was nothing else to do but to comply with Com. Task Force 71's order for the destruction of the boat on the 10th of July

That makes me think that the mine doors were open due to the post-stranding jettisoning of mines, and had become lodged from all the movement as they tried to get her off?

That's her on the reef: