German submarine U-186

German submarine U-186 was a Type IXC/40 U-boat of the Nazi German Kriegsmarine built for service during World War II. Her keel was laid down on 24 July 1941 by AG Weser in Bremen as 'werk' 1026. She was launched on 11 March 1942 and commissioned on 10 July with Korvettenkapitän Siegfried Hesemann in command.

The U-boat's service began with training as part of the 4th U-boat Flotilla. She then moved to the 10th flotilla on 1 January 1943 for operations. The submarine carried out two patrols and was a member of nine wolf packs. She sank three ships totalling.

She was sunk by a British destroyer in May 1943.

1st patrol
U-186's first patrol took her from Kiel, across the North Sea and into the Atlantic Ocean through the 'gap' between Iceland and the Faroe Islands. She sank the Ocean Vagabond on 11 January 1943 south of Iceland. This ship had already been damaged by U-513 in September 1942. U-186 also sank the Hastings and the Eulima on 23 February 1943 about 310 mi south of Cape Race (Newfoundland). She arrived at Lorient in occupied France, on 5 March.

2nd patrol and loss
The boat departed Lorient on 17 April 1943. On 12 May she was sunk northwest of the Azores by depth charges dropped by the British destroyer HMS Hesperus. Fifty three men died. There were no survivors.