An optical observation device is connected to an extendable and retractable snorkel tube for above-water observation during the snorkel travel (travel at periscope depth) of the submarine. The optical observation device is designed as a compact unit which consists of an optronics unit with a short-travel drive. The compact unit is assembled on the snorkel tube. At least one further compact unit is provided which comprises at least one communication arrangement with a short-travel drive, wherein this further compact unit is likewise provided on the snorkel tube.