German submarine U-2521

German submarine U-733 was a Type VIIC U-boat of Nazi Germany's Kriegsmarine during World War II. The submarine was laid down on 13 October 1941 at the Schichau-Werke yard at Danzig, launched on 5 September 1942, and commissioned on 14 November 1942 under the command of Oberleutnant zur See Wilhelm von Trotha.

German submarine U-794 was a Type XVIIA U-boat of Nazi Germany's Kriegsmarine during the Second World War. She was one of a small number of U-boats fitted with Hellmuth Walter's high test peroxide propulsion system, which offered a combination of air-independent propulsion and high submerged speeds. She spent the war as a trials vessel and was scuttled on 5 May 1945 in Gelting Bay. U-794 was built by Friedrich Krupp Germaniawerft, Kiel. The keel was laid down on 1 February 1943, the boat was launched on 7 October. She was commissioned on 14 November. The Feldpost Number was M 52 496. U-794 did not undertake any combat patrols and was instead assigned as a trials boat at first to the 5th U-boat Flotilla, followed by the 8th U-boat Flotilla, before returning to the 5th flotilla for the rest of the war. In late March 1944, Admiral Karl Dönitz and four other admirals took part in a trial of U-794. Although they were enthusiastic, the boat, designed for high underwater speed (over 20 m.p.h.) was difficult to manoeuvre, and the keel to beam ratio was too high.

German submarine U-721 was a Type VIIC U-boat of Nazi Germany's Kriegsmarine during World War II. The submarine was laid down on 16 November 1942 at the H. C. Stülcken Sohn yard at Hamburg, launched on 23 July 1943, and commissioned on 8 November 1943 under the command of Oberleutnant zur See Otto Wollschläger.

Gelting Bay (German: Geltinger Bucht, Danish: Gelting Bugt), sometimes also the Bay of Gelting, is a bight of the Baltic Sea on the northeastern coast of the region of Anglia at the exit to the Flensburg Fjord near the town of Gelting. The bay extends from Habernis in the northwest via Wackerballig to the south to the nature reserve of Geltinger Birk in the east. The length of the shoreline along the bay is about 15 kilometres. There are currently no commercial shipping routes across the bay. The coastal region belongs to the district of Geltinger Bucht with its head office in Steinbergkirche. The land around Gelting Bay is dominated by agriculture and tourism, the bay itself by sailing and some fishing.

Z43 was a Type 1936B destroyer built for the Kriegsmarine (German Navy) during World War II. Completed in mid-1944, the ship spent the war in the Baltic Sea, escorting German ships, laying minefields, and bombarding Soviet forces. She participated in a minelaying operation in December 1944, where her sister ships Z35 and Z36 were sunk when they accidentally entered a German minefield. She was badly damaged by a mine on 10 April 1945, and scuttled on 3 May of that same year.

Niesgrau (Danish: Nisvrå) is a municipality in the district of Schleswig-Flensburg, in Schleswig-Holstein, northern Germany near the Danish border.

Steinberg (Danish: Stenbjerg) is a municipality in the district of Schleswig-Flensburg, in Schleswig-Holstein, Germany.

Steinbergkirche (Danish: Stenbjergkirke) is a municipality in the district of Schleswig-Flensburg, in Schleswig-Holstein, Germany. It is situated near the Baltic Sea coast, approx. 30 km (19 mi) northeast of Schleswig, and 22 km (14 mi) east of Flensburg. Steinbergkirche is the seat of the Amt ("collective municipality") Geltinger Bucht.

Kegnæs (German: Kekenis) is a peninsula on the southern coast of Als in Denmark.

Sønderborg Castle (Danish: Sønderborg Slot) is located in the town of Sønderborg, Denmark on the island of Als in South Jutland. It houses a museum focusing on the history and culture of the area. The castle is located in the middle of the town, in a park setting overlooking Als Fjord. The museum is open year-round.

Sønderborg (Danish pronunciation: [ˈsønɐˌpɒˀ]; German: Sonderburg [ˈzɔndɐbʊʁk] ) is a Danish town in the Region of Southern Denmark. It is the main town and the administrative seat of Sønderborg Municipality (Kommune). The town has a population of 28,137 (1 January 2023), in a municipality of 74,380. In recent times, Sønderborg is a center for trade, tourism, industry, and education in the region of Southern Denmark. The town is the headquarters for several industrial companies. Sønderburg joined the UNESCO Global Network of Learning Cities in 2016.

Sønderborg station (Danish: Sønderborg Banegård or Sønderborg Station, previously Sønderborg H) is a railway station serving the city of Sønderborg in Southern Jutland, Denmark. The station is located on the west side of the Alssund, next to the Alsion science and culture centre. Sønderborg station is the eastern terminus of the Tinglev–Sønderborg railway line, which connects it to the Fredericia–Padborg railway line and the rest of the Danish rail network at Tinglev. The station opened in 1901. It offers frequent direct InterCity services to Kolding, Odense and Copenhagen.