O 20, laid down as K XX, was a O 19-class submarine of the Royal Netherlands Navy that saw service during World War II.

By early December 1941, O 20 had been stationed at Singapore Submarine Base and was under the command of the British Eastern Fleet.

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.

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 to loose the submarine from the seabed but also alerted the destroyers to O 20's position by releasing bubbles.

The commander decided to empty a fuel tank to escape even faster, which rose the sub even higher in the water exposing the diesel exhaust pipes.

[3] After daylight, Uranami rescued the 32 survivors, having dropped depth charges throughout the remainder of the night to keep sharks away.

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.

[3] They found her wreck approximately 35 nautical miles (65 km; 40 mi) northeast of Kota Baru, Malaysia, at a depth of about 144 feet (44 m).

The divers retrieved a deck phone from the submarine in order to positively identify it, but otherwise left the wreck alone, as it was likely the gravesite of six seamen and their commanding officer.