From the article: "It's a so-called wet submarine, meaning that it fills with water when submerged, so the driver has to wear a wetsuit and breathe air from a t

From the article: "It's a so-called wet submarine, meaning that it fills with water when submerged, so the driver has to wear a wetsuit and breathe air from a tank. (The dry passenger compartment shown in the movie was a set.)"