'Isar' was a U-boat wolfpack operation in the North Atlantic, in tandem with the 'Inn' wolfpack, against the ONS.7 convoy (10/15 May 1943).

The wolfpack comprised U-304, U-418, U-645 and U-952, and neither lost any of its own number nor sank any ship. On 15 May the 'Isar', 'Inn' and 'Nahe' wolfpacks were combined to create the two 'Donau' wolfpacks.