Laid Down:31 May 1965
Launched:3 October 1965
Purchased:11 July 1990
Commissioned:10 October 1990
Fate:in service
General Characteristics
Displacement:370 tons surfaced, 435 tons submerged
Length:47.20 meters
Beam:4.70 meters
Draught:3.80 meters
Propulsion:two MTU 1100 hp diesel engines, one 1700 hp electric motor
Speed:10 knots surfaced, 17 knots submerged
Complement:24 officers and men
Armament:eight 533mm (21-inch) torpedo tubes, eight torpedoes
KDM Sælen (S323), is one of the three Tumleren-class small coastal submarines of the Kongelige Danske Marine (Royal Danish Navy). She was built as a Type 207 submarine by Rheinstahl-Nordseewerke of Emden, Germany in 1965 for the Kongelige Norske Marine (Royal Norwegian Navy) and served for 25 years as KNM Uthaug before being purchased by Denmark in 1990. Her international call sign is OUCJ.

On 4 December 1990, Sælen sank while being towed from Copenhagen to Aarhus. On 17 December, she was raised by the German floating crane Roland and taken to Aarhus for repair. On 10 August 1993, diving approval was issued and the boat was recommissioned.

Sælen served in the 2003 invasion of Iraq from May 2002 until June 2003. To speed her return to her homeport of Frederikshavn after 385 days of deployment in the Mediterranean Sea and the Persian Gulf, she was transported on board the heavy-lift ship Grietje.

"Sælen" means "seal" in English.