Repairs were fully completed by 2 December, and she began post-refit trials. On 17 December, she was sailing off the Isle of Wight. The trial was being conducted at night, in heavy seas and with a strong north-east wind in complete darkness. She was conducting steaming exercises over a measured mile, 8 nmi (9.2 mi; 15 km) west-south-west of St. Catherine's Point. On one of the passes, she struck a mine. The explosion caused major structural damage forward, and her own speed drove her under. She sank within four minutes, taking 196 crewmen and yard workers, who were on board for the trials, to the bottom. There were only 19 survivors. The mine was probably one of those laid by the Luftwaffe along the Channel coast in no apparent pattern.

Her sinking was not made public until 26 December 1940.