Halt die Luft an alter Gauner - Der Stockfisch und das Stinktier (1976)

Two old sea dogs are fighting to the teeth for customers for a coastal cruise. Three crooks turn up at the resort and try to get a briefcase full of valuable jewelry out of the three-mile zone. A rich "Frenchwoman" is also involved in the affair. An insurance agent mingles with the tourists without being recognized in order to track down the jewel thieves.