Updated: January 26, 2018

Between the TV version's first and second seasons, the Seaview miniatures were extensively revised. Dated May 1965 the drawings penned by William Creber (who also designed the Flying Sub itself) stated "modifications to be applied to all miniatures." The number of bow windows was reduced from eight on two levels of four each to a single row of four (actually two with a dividing girder.) This then matched the interior set with the exterior miniatures but with the added detrimental affects of a more bulbous frontal appearance and a reduction in apparent overall size of the vessel. The Control Room, previously located on an upper level, was moved forward on a lower level ahead of the conning tower, to connect directly with the Observation Room, and a large hangar bay was added to the bow, beneath the Observation Room/Control Room combination.

This hangar held the 36 foot wide and long, flying submersible, aptly called the "Flying Sub" or "FS-1", implying that there were several more back at the base, which would have to be the case since several Flying Subs were lost to mishaps or combat during the run of the show. (Promotional materials published between the first and second seasons referred to it as the Flying Fish, but the name was evidently dropped prior to the start of filming and was never used in the show.) It was deployed through bomb-bay like doors. As it broke the surface, its engines could generate enough thrust for the vehicle to take off and fly at supersonic speeds. The Flying Sub was also nuclear powered.