HNLMS O 20

O 20, laid down K XX was a O 19-class submarine of the Royal Netherlands Navy that saw service during World War II. O 20 along with her sister ship O 19 were the first boats in the world to be equipped with a submarine snorkel that allowed the submarine to run its diesel engines while submerged.

Ship history
O 20 was laid down 15 June 1936 as the K XX. After which at some point she was renamed O 20. She was launched on 31 January 1939, and on 28 August 28 of the same year she was commissioned in the Dutch navy.

She was put into a squadron that consisted of two submarines: O 20 and O 15, and the sloop HNLMS Van Kinsbergen (1939). This squadron departed the Netherlands for the Netherlands West Indies on either 2 or 3 October 1939.

By December 1939 O 20 reached the Dutch East Indies via the Panama Canal.

World War II
On 10 May 1940 Germany attacked the Netherlands. 7 December 1941, the Japanese attack Pearl Harbor, brought the US into the war. The Netherlands followed suit hours later. By early December 1941, O 20 has been stationed at Singapore Submarine Base and is under the command of the British Eastern Fleet.

On 14 December 1941 O 20 was under orders to patrol the South China Sea. On the 14th, two battleships and six cruisers were sighted, O 20 and O 19 were given orders to gain position on the enemy ships. The two subs would split paths en route to the target when 13 transports were spotted off Patani, Thailand and another 20 off Kota Bharu, Malaysia.

Given a new patrol route, O 20 spotted Japanese destroyers off and on from December 17 to 19th. On the 19th at 7:00, she spied two Japanese transports being escorted by two destroyers. In a few hours a third destroyer joined them. These destroyers were the Ayanami, the Uranami, and the Yugiri.

At 11:00, O 20 was spotted by enemy planes which dropped two bombs on the submarine and alerted the destroyers to her presence. The submarine dove and was able to avoid the bombs, but the destroyers began to drop depth charges which soon destroyed the sub's listening device and caused other minor damage.

The destroyers scanned the bay for O 20, dropping eight depth charges every half hour. Some of these detonated directly above the submarine, but were set to detonate too shallow to badly damage it. (It turned out that the next deepest setting would have buried the charges in the mud)

In order to escape, the commander ordered full speed ahead with all planes set to rise, but O 20 had become mired in the mud. An air tank was blown in an attempt to loose the submarine from the seabed, but also ended up alerting the destroyers to O 20's position by releasing bubbles.

That night, the commander attempted to surface to escape at full speed, but was detected by a new Japanese sonar. Two more tanks were blown and the sub surfaced at a 25° angle and engines were set to full speed. Because of some pre-existing defects O 20 began to take on water at the screw shafts.

The hatch was opened and with no enemy ships in sight, the machine guns were not manned or prepared. The commander decided to empty a fuel tank in order to escape even faster, which rose the sub even higher in the water exposing the diesel exhaust pipes. Due to more pre-existing damage coupled with damage from the depth charges, the pipes began to spark, giving away the O 20's position to anyone who looked in her direction. The commander decided to do nothing.

After 20 minutes of running in this manner, one of the destroyers closed in, spotted the O 20 with her searchlight and opened fire. The shot missed. The commander now ordered the machine guns manned, and the ship turned about to fire the torpedoes. She couldn't get in position until after the fourth volley, which struck the Conn Tower and main hull. O 20 returned fire with the 40 mm machine gun. The port side torpedo was ordered to be fired, but because of extreme vibrations due to the speed, both sides fired. Both torpedoes missed.

The sub badly damaged, the commander decided then that there was no hope for escape, and ordered all hands on deck. He then ordered the sub be scuttled by flooding all the main ballast tanks. The sub descended under the water, still running at full speed, as the crew floated above. The destroyer, apparently not noticing that the crew had abandoned ship, followed the sub, cutting through the crew at 20 kn, and dropped depth charges on the now abandoned sub.

After daylight, Uranami rescued the 32 survivors, having dropped depth charges throughout the remainder of the night to keep sharks away. Seven men, including the commander were found to be missing. The commander was known to not have been wearing his life vest, which may have also been the cause of the other six deaths. An alternative suggestion is that since the six men all worked in the engine room, they may have not been warned in time to evacuate the ship before it was scuttled.

The shipwreck
On 12 June 2002 a group of 7 Dutch divers associated with the International Association for Handicapped Divers participated in a dive expedition to locate the O 20.

The wreck is located approximately 35 nmi North-East of Kota Baru, Malaysia at a depth of about 144 ft (44 m). The divers report that the masts are no longer visible, the snort is gone, and that the bridge was shelled so badly it could be seen through easily. The divers retrieved a deck phone from the sub in order to positively identify it, but left the wreck alone, as it was likely the gravesite of six seamen and their commander.