German submarine U-161 was a Type IXC U-boat of Nazi Germany's Kriegsmarine built for service during World War II.

The submarine was powered by two MAN M 9 V 40/46 supercharged four-stroke, nine-cylinder diesel engines producing a total of 4,400 metric horsepower (3,240 kW; 4,340 shp) for use while surfaced, two Siemens-Schuckert 2 GU 345/34 double-acting electric motors producing a total of 1,000 metric horsepower (740 kW; 990 shp) for use while submerged.

[2] The submarine's first patrol took her from Kiel on 3 January 1942, across the North Sea and into the Atlantic Ocean through the gap between the Faroe and Shetland Islands.

U-161's second sortie proved to be successful, damaging British Consul and Mokihana on 19 February 1942 while the ships rode at anchor in the Gulf of Paria off Port of Spain, Trinidad.

Then, daringly, she made her way at night through the narrow passage into Castries Harbour, St Lucia where she damaged the Lady Nelson and Umtata.

On 15 March 1942, while en route alone from Curaçao, Netherlands West Indies to Antigua, British West Indies, the Speedwell-class USCGC Acacia, (formerly the U.S. Army mine planter General John P. Story transferred to the United States Lighthouse Service at no cost in 1922,[5]) was sunk by gunfire from U-161 approximately 150 miles south of Port-au-Prince, Haiti.

Having commenced the return leg to France, she encountered Fairport 500 nmi (930 km; 580 mi) north of St. Thomas, Virgin Islands on 16 July and sank her.

She damaged the light cruiser HMS Phoebe six miles and 282° from Pointe Noire, French Equatorial Africa on 23 October 1942 and sank the West Humhaw 60 nmi (110 km; 69 mi) southwest of Takoradi in Ghana on 8 November.

The boat's fifth patrol involved another Atlantic crossing and sinking a second sailing ship, Angelus, north of Bermuda, again with gunfire.