Das Boot ending explained

What happens

After surviving the Atlantic, the crew reach La Rochelle to cheers. Then British aircraft bomb the harbour. Many of the men die, the captain is fatally wounded, and he watches the boat sink before he dies. Werner survives.

The last image

The boat goes down in the harbour as the dying captain watches, with Werner, the survivor, looking on.

What it says

The ending is not a twist. After so much skill and endurance, the men die at the very moment they feel safe. The film is saying survival depends on chance, not skill or virtue, and that this war offers no glory, only waste.